Bitcoin Wiki - User contributions [en]

Help:FAQ

2014-09-02T13:42:23Z

DoctorBTC: /* Can I buy bitcoins with Paypal? */

Here you will find answers to the most commonly asked questions.

== General ==
=== What is Bitcoin? ===
Bitcoin is a distributed peer-to-peer digital currency that can be transferred instantly and securely between any two people in the world. It's like electronic cash that you can use to pay friends or merchants.

=== What are bitcoins? ===
Bitcoins are the unit of currency of the Bitcoin system. A commonly used shorthand for this is “BTC” to refer to a price or amount (e.g. “100 BTC”).
There are such things as [[physical bitcoins]], but ultimately, a bitcoin is just a number associated with a [[Address|Bitcoin Address]]. A physical bitcoin is simply an object, such as a coin, with the number carefully embedded inside. See also an [[Introduction|easy intro]] to Bitcoin.

=== How can I get bitcoins? ===

There are a variety of ways to acquire bitcoins:
* You can buy bitcoins from [http://coinbase.com/?r=514b6eb6a18f2fdde50000db&utm_campaign=user-referral&src=referral-link Coinbase].
* Accept bitcoins as payment for goods or services.
* The most common way to buy bitcoins are the [[Buying bitcoins|Bitcoin Exchanges]]
* Visit [http://bitcoinx.io bitcoinx.io] for peer-to-peer ratings and reviews of bitcoin exchanges to see where to buy bitcoins
* Find someone to trade cash for bitcoins in-person through a [https://en.bitcoin.it/wiki/Category:Directories local directory].
* Participate in a [[Pooled mining|mining pool]].
* If you have a lot of mining hardware, you can solo mine and attempt to create a new [[block]] (currently yields 25 bitcoins plus transaction fees).
* Visit sites that provide [[Trade#Free_Samples_and_Offers|free samples and offers]].

===Does Bitcoin guarantee an influx of free money?===

Since Bitcoin is a new technology, what it is and how it works may be initially unclear. Bitcoin is sometimes presented as being one of three things:
<ol style="list-style-type: upper-alpha;">
<li>Some sort of online 'get-rich-quick' scam.</li>
<li>A loophole in the market economy, the installation of which guarantees a steady influx of cash.</li>
<li>A sure investment that will almost certainly yield a profit.</li>
</ol>
In fact, none of the above are true. Let's look at them independently.

;Is Bitcoin a 'get-rich-quick' scheme?
:If you've spent much time on the Internet, you've probably seen ads for many 'get-rich-quick' schemes. These ads usually promise huge profits for a small amounts of easy work. Such schemes are usually pyramid/matrix-style schemes that make money from their own employees and offer nothing of any real value. Most convince one to buy packages that will make them earn hundreds a day, which in fact have the buyer distribute more such ads, and make minute profits.

:Bitcoin is in no way similar to these schemes. Bitcoin doesn't promise windfall profits. There is no way for the developers to make money from your involvement or to take money from you. That bitcoins are nearly impossible to acquire without the owner's consent represents one of its greatest strengths. Bitcoin is an experimental, virtual currency that may succeed or may fail. None of its developers expect to get rich off of it.

:A more detailed answer to this question can be found [http://bitcointalk.org/?topic=7815.0 here].

;Will I make money by installing the client?
:Most people who use Bitcoin don't earn anything by doing so, and the default client has no built-in way to earn Bitcoins. A small minority of people with dedicated, high-performance hardware do earn some Bitcoins by "''mining''" (generating new bitcoins, see [[#What is mining?|What is mining?]]) with special software, but joining Bitcoin shouldn't be construed as being the road to riches. Most Bitcoin users get involved because they find the project conceptually interesting and don't earn anything by doing so. This is also why you won't find much speculation about the political or economic repercussions of Bitcoin anywhere on this site: Bitcoin developers owe their dedication to the project's intellectual yieldings more than to those of a monetary nature. Bitcoin is still taking its first baby steps; it may go on to do great things but right now it only has something to offer those chasing conceptually interesting projects or bleeding edge technology.

;As an investment, is Bitcoin a sure thing?
:Bitcoin is a new and interesting electronic currency, the value of which is not backed by any single government or organization. Like other currencies, it is worth something partly because people are willing to trade it for goods and services. Its exchange rate fluctuates continuously, and sometimes wildly. It lacks wide acceptance and is vulnerable to manipulation by parties with modest funding. Security incidents such as website and account compromise may trigger major sell-offs. Other fluctuations can build into positive feedback loops and cause much larger exchange rate fluctuations. Anyone who puts money into Bitcoin should understand the risk they are taking and consider it a high-risk currency. Later, as Bitcoin becomes better known and more widely accepted, it may stabilize, but for the time being it is unpredictable. Any investment in Bitcoin should be done carefully and with a clear plan to manage the risk.

=== Can I buy bitcoins with Paypal? ===

It is possible to buy [[physical bitcoins]] with PayPal but it is otherwise difficult and/or expensive to do so for non-physical bitcoins, because of significant risk to the seller.

There is a [https://www.virwoxx.com workaround] that can be done in order to use Paypal to buy Bitcoins but it holds within it higher transaction fees. Using the [https://www.virwoxx.com Virtual World Exchange] you can buy Second Life Lindens (SLL) with Paypal and then convert your SLL to Bitcoins. This process will charge you transaction fees of around 6% but will let you purchase Bitcoins pretty quickly as opposed to a wire transfer. The reason this method works is because you do not buy Bitcoins with Paypal directly, you only buy SLL with Paypal (which is acceptable by Paypal's TOS) and then exchange your SLL to Bitcoin.

While it is possible to find an individual who wishes to sell Bitcoin to you via Paypal, (perhaps via [http://www.bitcoin-otc.com/ #bitcoin-otc] ) most exchanges do not allow funding through PayPal. This is due to repeated cases where someone pays for bitcoins with Paypal, receives their bitcoins, and then fraudulently complains to Paypal that they never received their purchase. PayPal often sides with the fraudulent buyer in this case, which means any seller needs to cover that risk with higher fees or refuse to accept PayPal altogether.

Buying Bitcoins from individuals this way is still possible, but requires the seller to have some trust that the buyer will not file a claim with PayPal to reverse the payment.

=== Where can I find a forum to discuss Bitcoin? ===

Please visit the [[Bitcoin:Community_portal#Bitcoin_Community_Forums_on_various_platforms|Community Portal]] for links to Bitcoin-related forums.

=== How are new bitcoins created? ===

New bitcoins are generated by the network through the process of "[[#What is mining?|''mining'']]". In a process that is similar to a continuous raffle draw, mining nodes on the network are awarded bitcoins each time they find the solution to a certain mathematical problem (and thereby create a new [[block]]). Creating a block is a [[proof of work]] with a difficulty that varies with the overall strength of the network. The reward for solving a block is [[Controlled Currency Supply|automatically adjusted]] so that, ideally, every four years of operation of the Bitcoin network, half the amount of bitcoins created in the prior 4 years are created. A maximum of {{formatnum:10499889.80231183}} bitcoins were created in the first 4 (approx.) years from January 2009 to November 2012. Every four years thereafter this amount halves, so it should be {{formatnum:5250000}} over years 4-8, {{formatnum:2625000}} over years 8-12, and so on. Thus the total number of bitcoins in existence can never exceed {{formatnum:20999839.77085749}} and counting. See [[Controlled Currency Supply]].

Blocks are [[Mining|mined]] every 10 minutes, on average and for the first four years ({{formatnum:210000}} blocks) each block included 50 new bitcoins. As the amount of processing power directed at mining changes, the difficulty of creating new bitcoins changes. This difficulty factor is calculated every 2016 blocks and is based upon the time taken to generate the previous 2016 blocks. See [[Mining]].

=== What's the current total number of bitcoins in existence? ===

[http://blockexplorer.com/q/totalbc Current count]. Also see [https://blockchain.info/charts/total-bitcoins Total bitcoins in circulation chart]

The number of blocks times the coin value of a block is the number of coins in existence. The coin value of a block is 50 BTC for each of the first {{formatnum:210000}} blocks, 25 BTC for the next {{formatnum:210000}} blocks, then 12.5 BTC, 6.25 BTC and so on.

=== How divisible are bitcoins? ===

A bitcoin can be divided down to 8 decimal places. Therefore, 0.00000001 BTC is the smallest amount that can be handled in a transaction. If necessary, the protocol and related software can be modified to handle even smaller amounts.

=== What do I call the various denominations of bitcoin? ===

There is a lot of discussion about the naming of these fractions of bitcoins. The leading candidates are:

* 1 BTC = 1 bitcoin
* 0.01 BTC = 1 cBTC = 1 centibitcoin (also referred to as bitcent)
* 0.001 BTC = 1 mBTC = 1 millibitcoin (also referred to as mbit (pronounced em-bit) or millibit or even bitmill)
* 0.000 001 BTC = 1 μBTC = 1 microbitcoin (also referred to as ubit (pronounced yu-bit) or microbit)

The above follows the accepted international SI prefixes for hundredths, thousandths, and millionths. There are many arguments against the special case of 0.01 BTC since it is unlikely to represent anything meaningful as the Bitcoin economy grows (it certainly won't be the equivalent of 0.01 USD, GBP or EUR). Equally, the inclusion of existing national currency denominations such as "cent", "nickel", "dime", "pence", "pound", "kopek" and so on are to be discouraged; this is a worldwide currency.

One exception is the "satoshi" which is smallest denomination currently possible

* 0.000 000 01 BTC = 1 satoshi (pronounced sa-toh-shee)
which is so named in honour of Satoshi Nakamoto, the pseudonym of the inventor of Bitcoin.

For an overview of all defined units of Bitcoin (including less common and niche units), see [[Units]].

Further discussion on this topic can be found on the forums here:

* [https://bitcointalk.org/index.php?topic=14438.msg195287#msg195287 We need names]
* [https://bitcointalk.org/index.php?topic=8282.0 What to call 0.001 BTC]

=== How does the halving work when the number gets really small? ===

Eventually the reward will go from 0.00000001 BTC to zero and no more bitcoins will be created.

The block reward calculation is done as a right bitwise shift of a 64-bit signed integer, which means it is divided by two and rounded down. The integer is equal to the value in BTC * 100,000,000 since internally in the reference client software, all Bitcoin balances and values are stored as unsigned integers.

With an initial block reward of 50 BTC, it will take many 4-year periods for the block reward to reach zero.

=== How long will it take to generate all the coins? ===

The last block that will generate coins will be block #6,929,999 which should be generated at or near the year 2140. The total number of coins in circulation will then remain static at 20,999,999.9769 BTC.

Even if the allowed precision is expanded from the current 8 decimals, the total BTC in circulation will always be slightly below 21 million (assuming everything else stays the same). For example, with 16 decimals of precision, the end total would be 20,999,999.999999999496 BTC.

=== If no more coins are going to be generated, will more blocks be created? ===

Absolutely! Even before the creation of coins ends, the use of [[transaction fee|transaction fees]] will likely make creating new blocks more valuable from the fees than the new coins being created. When coin generation ends, these fees will sustain the ability to use bitcoins and the Bitcoin network. There is no practical limit on the number of blocks that will be mined in the future.

=== But if no more coins are generated, what happens when Bitcoins are lost? Won't that be a problem? ===

Because of the law of supply and demand, when fewer bitcoins are available the ones that are left will be in higher demand, and therefore will have a higher value. So, as Bitcoins are lost, the remaining bitcoins will eventually increase in value to compensate. As the value of a bitcoin increases, the number of bitcoins required to purchase an item '''de'''creases. This is a [[Deflationary spiral|deflationary economic model]]. As the average transaction size reduces, transactions will probably be denominated in sub-units of a bitcoin such as millibitcoins ("Millies") or microbitcoins ("Mikes").

The Bitcoin protocol uses a base unit of one hundred-millionth of a Bitcoin ("a Satoshi"), but unused bits are available in the protocol fields that could be used to denote even smaller subdivisions.

=== If every transaction is broadcast via the network, does Bitcoin scale? ===
The Bitcoin protocol allows lightweight clients that can use Bitcoin without downloading the entire transaction history. As traffic grows and this becomes more critical, implementations of the concept will be developed. Full network nodes will at some point become a more specialized service.

With some modifications to the software, full Bitcoin nodes could easily keep up with both VISA and MasterCard combined, using only fairly modest hardware (a single high end server by todays standards). It is worth noting that the MasterCard network is structured somewhat like Bitcoin itself - as a peer to peer broadcast network.

Learn more about [[Scalability]].

==Economy==
=== Where does the value of Bitcoin stem from? What backs up Bitcoin? ===
Bitcoins have value because they are useful and because they are [[Controlled Currency Supply|scarce]]. As they are accepted by more merchants, their value will [http://en.wikipedia.org/wiki/Sticky_%28economics%29 stabilize]. See the [[Trade|list of Bitcoin-accepting sites]].

When we say that a currency is backed up by gold, we mean that there's a promise in place that you can exchange the currency for gold. Bitcoins, like dollars and euros, are not backed up by anything except the variety of merchants that accept them.

It's a common misconception that Bitcoins gain their value from the cost of electricity required to generate them. Cost doesn't equal value – hiring 1,000 men to shovel a big hole in the ground may be costly, but not valuable. Also, even though scarcity is a critical requirement for a useful currency, it alone doesn't make anything valuable. For example, your fingerprints are scarce, but that doesn't mean they have any exchange value.

Alternatively it needs to be added that while the law of supply and demand applies it does not guarantee value of Bitcoins in the future. If confidence in Bitcoins is lost then it will not matter that the supply can no longer be increased, the demand will fall off with all holders trying to get rid of their coins. An example of this can be seen in cases of state currencies, in cases when the state in question dissolves and so no new supply of the currency is available (the central authority managing the supply is gone), however the demand for the currency falls sharply because confidence in its purchasing power disappears. Of-course Bitcoins do not have such central authority managing the supply of the coins, but it does not prevent confidence from eroding due to other situations that are not necessarily predictable.

=== Is Bitcoin a bubble? ===
Yes, in the same way as the euro and dollar are. They only have value in exchange and have no inherent value. If everyone suddenly stopped accepting your dollars, euros or bitcoins, the "bubble" would burst and their value would drop to zero. But that is unlikely to happen: even in Somalia, where the government collapsed 20 years ago, [http://en.wikipedia.org/wiki/Somali_shilling Somali shillings] are still accepted as payment.

=== Is Bitcoin a Ponzi scheme? ===
In a Ponzi Scheme, the founders persuade investors that they’ll profit. Bitcoin does not make such a guarantee. There is no central entity, just individuals building an economy.

A ponzi scheme is a zero sum game. Early adopters can only profit at the expense of late adopters. Bitcoin has possible win-win outcomes. Early adopters profit from the rise in value. Late adopters, and indeed, society as a whole, benefit from the usefulness of a stable, fast, inexpensive, and widely accepted p2p currency.

The fact that early adopters benefit more doesn't alone make anything a Ponzi scheme. All good investments in successful companies have this quality.

=== Doesn't Bitcoin unfairly benefit early adopters? ===
Early adopters in Bitcoin are taking a risk and invested resources in an unproven technology. By so doing, they help Bitcoin become what it is now and what it will be in the future (hopefully, a ubiquitous decentralized digital currency). It is only fair they will reap the benefits of their successful investment.

In any case, any bitcoin generated will probably change hands dozens of time as a medium of exchange, so the profit made from the initial distribution will be insignificant compared to the total commerce enabled by Bitcoin. Many of the earliest users of Bitcoin have traded their coins at valuations below $1 US, or other amounts which are small compared to contemporary prices.

===Won't loss of wallets and the finite amount of Bitcoins create excessive deflation, destroying Bitcoin? ===
Worries about Bitcoin being destroyed by deflation are not entirely unfounded. Unlike most currencies, which experience inflation as their founding institutions create more and more units, Bitcoin will likely experience gradual deflation with the passage of time. Bitcoin is unique in that only a small amount of units will ever be produced (twenty-one million to be exact), this number has been known since the project's inception, and the units are created at a predictable rate.

Also, Bitcoin users are faced with a danger that doesn't threaten users of any other currency: if a Bitcoin user loses his wallet, his money is gone forever, unless he finds it again. And not just to him; it's gone completely out of circulation, rendered utterly inaccessible to anyone. As people will lose their wallets, the total number of Bitcoins will slowly decrease.

Therefore, Bitcoin seems to be faced with a unique problem. Whereas most currencies inflate over time, Bitcoin will mostly likely do just the opposite. Time will see the irretrievable loss of an ever-increasing number of Bitcoins. An already small number will be permanently whittled down further and further. And as there become fewer and fewer Bitcoins, the laws of supply and demand suggest that their value will probably continually rise.

Thus Bitcoin is bound to once again stray into mysterious territory, because no one exactly knows what happens to a currency that grows continually more valuable. Many economists claim that a low level of inflation is a good thing for a currency, but nobody is quite sure about what might happens to one that continually deflates. Although deflation could hardly be called a rare phenomenon, steady, constant deflation is unheard of. There may be a lot of speculation, but no one has any hard data to back up their claims.

That being said, there is a mechanism in place to combat the obvious consequences. Extreme deflation would render most currencies highly impractical: if a single Canadian dollar could suddenly buy the holder a car, how would one go about buying bread or candy? Even pennies would fetch more than a person could carry. Bitcoin, however, offers a simple and stylish solution: infinite divisibility. Bitcoins can be divided up and trade into as small of pieces as one wants, so no matter how valuable Bitcoins become, one can trade them in practical quantities.

In fact, infinite divisibility should allow Bitcoins to function in cases of extreme wallet loss. Even if, in the far future, so many people have lost their wallets that only a single Bitcoin, or a fraction of one, remains, Bitcoin should continue to function just fine. No one can claim to be sure what is going to happen, but deflation may prove to present a smaller threat than many expect.

For more information, see the [[Deflationary spiral]] page.

=== What if someone bought up all the existing Bitcoins? ===
Bitcoin markets are competitive -- meaning the price of a bitcoin will rise or fall depending on supply and demand at certain price levels. Only a fraction of bitcoins issued to date are found on the exchange markets for sale. So even though technically, a buyer with lots of money could buy all the bitcoins offered for sale, unless those holding the rest of the bitcoins offer them for sale as well, even the wealthiest, most determined buyer can't get at them.

Additionally, new currency continues to be issued daily and will continue to do so for decades; though over time the rate at which they are issued declines to insignificant levels. Those who are mining aren't obligated to sell their bitcoins so not all bitcoins will make it to the markets even.

This situation doesn't suggest, however, that the markets aren't vulnerable to price manipulation. It doesn't take significant amounts of money to move the market price up or down, and thus Bitcoin remains a volatile asset.

===What if someone creates a new block chain, or a new digital currency that renders Bitcoin obsolete?===

That the block chain cannot be easily forked represents one of the central security mechanisms of Bitcoin. Given the choice between two block chains, a Bitcoin miner always chooses the longer one - that is to say, the one with the more complex hash. Thusly, it ensures that each user can only spend their bitcoins once, and that no user gets ripped off.

As a consequence of the block chain structure, there may at any time be many different sub-branches, and the possibility always exists of a transaction being over-written by the longest branch, if it has been recorded in a shorter one. The older a transaction is though, the lower its chances of being over-written, and the higher of becoming permanent. Although the block chain prevents one from spending more Bitcoins than one has, it means that transactions can be accidentally nullified.

A new block chain would leave the network vulnerable to [[double-spending|double-spend]] attacks. However, the creation of a viable new chain presents considerable difficulty, and the possibility does not present much of a risk.

Bitcoin will always choose the longer Block Chain and determines the relative length of two branches by the complexities of their hashes. Since the hash of each new block is made from that of the block preceding it, to create a block with a more complex hash, one must be prepared to do more computation than has been done by the entire Bitcoin network from the fork point up to the newest of the blocks one is trying to supersede. Needless to say, such an undertaking would require a very large amount of processing power and since Bitcoin is continually growing and expanding, it will likely only require more with the passage of time.

A much more distinct and real threat to the Bitcoin use is the development of other, superior virtual currencies, which could supplant Bitcoin and render it obsolete and valueless.

A great deal of careful thought and ingenuity has gone into the development of Bitcoin, but it is the first of its breed, a prototype, and vulnerable to more highly-evolved competitors. At present, any threatening rivals have yet to rear their heads; Bitcoin remains the first and foremost private virtual currency, but we can offer no guarantees that it will retain that position. It would certainly be in keeping with internet history for a similar system built from the same principles to supersede and cast Bitcoin into obsolescence, after time had revealed its major shortcomings. Friendster and Myspace suffered similar fates at the hand of Facebook, Napster was ousted by Limeware, Bearshare and torrent applications, and Skype has all but crushed the last few disciples of the Microsoft Messenger army.

This may sound rather foreboding, so bear in mind that the introduction of new and possibly better virtual currencies will not necessarily herald Bitcoin's demise. If Bitcoin establishes itself sufficiently firmly before the inception of the next generation of private, online currencies so as to gain widespread acceptance and general stability, future currencies may pose little threat even if they can claim superior design. This is known as the network effect.

=== Is Bitcoin open to value manipulation? ===

The current low market cap of Bitcoin means that any investor with deep enough pockets can significantly change/manipulate the rate. Is this a problem?

This is only a problem if you are investing in Bitcoin for short period of time. A manipulator can't change the fundamentals, and over a period of 5-10 years, the fundamentals will win over any short term manipulations.

==Sending and Receiving Payments==

=== Why do I have to wait 10 minutes before I can spend money I received? ===

10 minutes is the average time taken to find a block. It can be significantly more or less time than that depending on luck; 10 minutes is simply the average case.

[[Blocks]] (shown as "confirmations" in the GUI) are how the Bitcoin achieves consensus on who owns what. Once a block is found everyone agrees that you now own those coins, so you can spend them again. Until then it's possible that some network nodes believe otherwise, if somebody is attempting to defraud the system by reversing a transaction. The more confirmations a transaction has, the less risk there is of a reversal. Only 6 blocks or 1 hour is enough to make reversal computationally impractical. This is dramatically better than credit cards which can see chargebacks occur up to three months after the original transaction!

Ten minutes was specifically chosen by [[Satoshi]] as a tradeoff between first confirmation time and the amount of work wasted due to chain splits. After a block is mined, it takes time for other miners to find out about it, and until then they are actually competing against the new block instead of adding to it. If someone mines another new block based on the old block chain, the network can only accept one of the two, and all the work that went into the other block gets wasted. For example, if it takes miners 1 minute on average to learn about new blocks, and new blocks come every 10 minutes, then the overall network is wasting about 10% of its work. Lengthening the time between blocks reduces this waste.

As a thought experiment, what if the Bitcoin network grew to include Mars? From the farthest points in their orbits, it takes about 20 minutes for a signal to travel from Earth to Mars. With only 10 minutes between new blocks, miners on Mars would always be 2 blocks behind the miners on Earth. It would be almost impossible for them to contribute to the block chain. If we wanted collaborate with those kinds of delays, we would need at least a few hours between new blocks.

[[File:TransactionConfirmationTimesExample.PNG]]

=== Do you have to wait until my transactions are confirmed in order to buy or sell things with Bitcoin? ===

YES, you do, IF the transaction is non-recourse. The Bitcoin reference software does not display transactions as confirmed until six blocks have passed (confirmations). As transactions are buried in the chain they become increasingly non-reversible but are very reversible before the first confirmation. Two to six confirmations are recommended for non-recourse situations depending on the value of the transactions involved.

When people ask this question they are usually thinking about applications like supermarkets. This generally is a recourse situation: if somebody tries to double-spend on a face-to-face transaction it might work a few times, but probabalistically speaking eventually one of the double-spends will get noticed, and the penalty for shoplifting charges in most localities is calibrated to be several times worse than the proceeds of a single shoplifting event.

Double-spends might be a concern for something like a snack machine in a low-traffic area with no nearby security cameras. Such a machine shouldn't honor zero-confirmation payments, and should instead use some other mechanism of clearing Bitcoin or validating transactions against reversal, see the wiki article [[Myths#Point_of_sale_with_bitcoins_isn.27t_possible_because_of_the_10_minute_wait_for_confirmation|here]] for alternatives.

Applications that require immediate payment processing, like supermarkets or snack machines, need to manage the risks. Here is one way to reverse an unconfirmed payment:

A [[Double-spending#Finney_attack|Finney attack]] is where an attacker mines a block containing a movement of some coins back to themselves. Once they find a block solution, they quickly go to a merchant and make a purchase, then broadcast the block, thus taking back the coins. This attack is a risk primarily for goods that are dispatched immediately, like song downloads or currency trades. Because the attacker can't choose the time of the attack, it isn't a risk for merchants such as supermarkets where you can't choose exactly when to pay (due to queues, etc). The attack can fail if somebody else finds a block containing the purchasing transaction before you release your own block, therefore, merchants can reduce but not eliminate the risk by making purchasers wait some length of time that's less than a confirm.

Because pulling off this attack is not trivial, merchants who need to sell things automatically and instantly are most likely to adjust the price to include the cost of reversal fraud, or elect to use special insurance.

=== I was sent some bitcoins and they haven't arrived yet! Where are they? ===

Don't panic! There are a number of reasons why your bitcoins might not show up yet, and a number of ways to diagnose them.

The latest version of the Bitcoin-Qt client tells you how far it has yet to go in downloading the blockchain. Hover over the icon in the bottom right corner of the client to learn your client's status.

If it has not caught up then it's possible that your transaction hasn't been included in a block yet.

You can check pending transactions in the network by going [https://www.biteasy.com here] or [http://blockchain.info here] and then searching for your address. If the transaction is listed here then it's a matter of waiting until it gets included in a block before it will show in your client.

If the transaction is based on a coin that was in a recent transaction then it could be considered a low priority transaction. Transfers can take longer if the transaction fee paid was not high enough. If there is no fee at all the transfer can get a very low priority and take hours or even days to be included in a block.

=== Why does my Bitcoin address keep changing? ===

Unlike postal or email addresses, Bitcoin addresses are single-use.
This means that whenever you want to receive a payment, you need to generate a new address.

While it is technically possible to receive coins multiple times with a single address, this compromises your wallet's security as well as the privacy of the entire Bitcoin network, and also makes it impossible to know for certain who sent the coins or why.

===How much will the transaction fee be?===

Some transactions might require a [[transaction fee]] for them to get confirmed in a timely manner. The transaction fee is processed by and received by the bitcoin miner. The most recent version of the Bitcoin client will estimate an appropriate fee when a fee might be required.

The fee is added to the payment amount. For example, if you are sending a 1.234 BTC payment and the client requires a 0.0005 BTC fee, then 1.2345 BTC will be subtracted from the wallet balance for the entire transaction and the address for where the payment was sent will receive a payment of 1.234 BTC.

A fee might be imposed because your transaction looks like a denial of service attack to the Bitcoin system. For example, it might be burdensome to transmit or it might recycle Bitcoins you recently received. The wallet software attempts to avoid generating burdensome transactions, but it isn't always able to do so: The funds in your wallet might be new or composed of many tiny payments.

Because the fee is related to the amount of data that makes up the transaction and not to the amount of Bitcoins being sent, the fee may seem extremely low (0.0005 BTC for a 1,000 BTC transfer) or unfairly high (0.004 BTC for a 0.02 BTC payment, or about 20%). If you are receiving tiny amounts (''e.g.'' as small payments from a mining pool) then fees when sending will be higher than if your activity follows the pattern of conventional consumer or business transactions.

As of Bitcoin 0.5.3 the required fee will not be higher than 0.05 BTC. For most users there is usually no required fee at all. If a fee is required it will most commonly be 0.0005 BTC.

=== What happens when someone sends me a bitcoin but my computer is powered off? ===

Bitcoins are not actually "sent" to your wallet; the software only uses that term so that we can use the currency without having to learn new concepts. Your wallet is only needed when you wish to spend coins that you've received.

If you are sent coins when your wallet client program is not running, and you later launch the wallet client program, the coins will eventually appear as if they were just received in the wallet. That is to say, when the client program is started it must download blocks and catch up with any transactions it did not already know about.

=== How long does "synchronizing" take when the Bitcoin client is first installed? What's it doing? ===

The popular Bitcoin client software from bitcoin.org implements a "full" Bitcoin node: It can carry out all the duties of the Bitcoin P2P system, it isn't simply a "client". One of the principles behind the operation of full Bitcoin nodes is that they don't assume that the other participants have followed the rules of the Bitcoin system. During synchronization, the software is processing historical Bitcoin transactions and making sure for itself that all of the rules of the system have been correctly followed.

In normal operation, after synchronizing, the software should use a hardly noticeable amount of your computer's resources.

When the wallet client program is first installed, its initial validation requires a lot of work from your computer's hard disk, so the amount of time to synchronize depends on your disk speed and, to a lesser extent, your CPU speed. It can take anywhere from a few hours to a day or so. On a slow computer it could take more than 40 hours of continuous synchronization, so check your computer's power-saving settings to ensure that it does not turn its hard disk off when unattended for a few hours. You can use the Bitcoin software during synchronization, but you may not see recent payments to you until the client program has caught up to the point where those transactions happened.

If you feel that this process takes too long, you can download a pre-synchronized blockchain from [http://eu2.bitcoincharts.com/blockchain/ http://eu2.bitcoincharts.com/blockchain/]. Alternatively, you can try an alternative "lite" client such as Multibit or a super-light client like electrum, though these clients have somewhat weaker security, are less mature, and don't contribute to the health of the P2P network.

==Networking==
=== Do I need to configure my firewall to run Bitcoin? ===

Bitcoin will connect to other nodes, usually on TCP port 8333. You will need to allow outgoing TCP connections to port 8333 if you want to allow your Bitcoin client to connect to many nodes. [[Testnet]] uses TCP port 18333 instead of 8333.

If you want to restrict your firewall rules to a few IPs, you can find stable nodes in the [[Fallback Nodes|fallback nodes list]].

=== How does the peer finding mechanism work? ===

Bitcoin finds peers primarily by forwarding peer announcements within its own network and each node saves a database of peers that it's aware of, for future use. In order to bootstrap this process Bitcoin needs a list of initial peers, these can be provided manually but normally it obtains them by querying a set of DNS domain names which have automatically updated lists, if that doesn't work it falls back to a built-in list which is updated from time to time in new versions of the software. In the reference software initial peers can also be specified manually by adding an addr.txt to the data directory or via the addnode parameter.

==Mining==
===What is mining?===
[[Mining]] is the process of spending computation power to secure Bitcoin transactions against reversal and introducing new Bitcoins to the system.

Technically speaking, mining is the calculation of a [[hash]] of the a block header, which includes among other things a reference to the previous block, a hash of a set of transactions and a [[nonce]]. If the hash value is found to be less than the current [[target]] (which is inversely proportional to the [[difficulty]]), a new block is formed and the miner gets the newly generated Bitcoins (25 per block at current levels). If the hash is not less than the current target, a new nonce is tried, and a new hash is calculated. This is done millions of times per second by each miner.

===Is mining used for some useful computation?===
The computations done when mining are internal to Bitcoin and not related to any other distributed computing projects. They serve the purpose of securing the Bitcoin network, which is useful.

===Is it not a waste of energy?===
Spending energy on creating and securing a free monetary system is hardly a waste. Also, services necessary for the operation of currently widespread monetary systems, such as banks and credit card companies, also spend energy, arguably more than Bitcoin would.

===Why don't we use calculations that are also useful for some other purpose?===
To provide security for the Bitcoin network, the calculations involved need to have some [http://bitcoin.stackexchange.com/questions/5617/why-are-bitcoin-calculation-useless/5618#5618 very specific features]. These features are incompatible with leveraging the computation for other purposes.

===How can we stop miners from creating zero transaction blocks?===
The incentive for miners to include transactions is in the fees that come along with them. If we were to implement some minimum number of transactions per block it would be trivial for a miner to create and include transactions merely to surpass that threshold. As the network matures, the block reward drops, and miners become more dependent on transactions fees to pay their costs, the problem of zero transaction blocks should diminish over time.

===How does the proof-of-work system help secure Bitcoin?===
Bitcoin uses the [[Hashcash]] proof of work with a minor adaption. To give a general idea of the mining process, imagine this setup:

payload = <some data related to things happening on the Bitcoin network>
nonce = 1
hash = [http://en.wikipedia.org/wiki/SHA2 SHA2]( [http://en.wikipedia.org/wiki/SHA2 SHA2]( payload + nonce ) )

The work performed by a miner consists of repeatedly increasing "nonce" until
the hash function yields a value, that has the rare property of being below a certain
target threshold. (In other words: The hash "starts with a certain number of zeroes",
if you display it in the fixed-length representation, that is typically used.)

As can be seen, the mining process doesn't compute anything special. It merely
tries to find a number (also referred to as nonce) which - in combination with the payload -
results in a hash with special properties.

The advantage of using such a mechanism consists of the fact, that it is very easy to check a result: Given the payload and a specific nonce, only a single call of the hashing function is needed to verify that the hash has the required properties. Since there is no known way to find these hashes other than brute force, this can be used as a "proof of work" that someone invested a lot of computing power to find the correct nonce for this payload.

This feature is then used in the Bitcoin network to secure various aspects. An attacker
that wants to introduce malicious payload data into the network, will need to do the
required proof of work before it will be accepted. And as long as honest miners have more
computing power, they can always outpace an attacker.

Also see [http://en.wikipedia.org/wiki/Hashcash Hashcash] and [http://en.wikipedia.org/wiki/Proof-of-work_system Proof-of-work system] and [http://en.wikipedia.org/wiki/SHA2 SHA2] and on Wikipedia.

===Why was the "Generate coin" option of the client software removed?===

The option wasn't removed, but it is now only accessible via the command-line or the configuration file. The reason for this is that many users were complaining after they turned on and expecting to receive coins. Without specialized mining hardware a user is exceptionally unlikely generate a block on their own at the network's current [[difficulty|security level]].

==Security==

===Could miners collude to give themselves money or to fundamentally change the nature of Bitcoin?===

There are two questions in here. Let's look at them separately.

;Could miners gang up and give themselves money?

Mining itself is the process of creating new blocks in the block chain. Each block contains a list of all the transactions that have taken place across the entire Bitcoin network since the last block was created, as well as a hash of the previous block. New blocks are 'mined', or rather, generated, by Bitcoin clients correctly guessing sequences of characters in codes called 'hashes,' which are created using information from previous blocks. Bitcoin users may download specialized 'mining' software, which allows them to dedicate some amount of their processing power – however large or small – to guessing at strings within the hash of the previous block. Whoever makes the right guess first, thus creating a new block, receives a reward in Bitcoins.

The block chain is one of the two structures that makes Bitcoin secure, the other being the public-key encryption system on which Bitcoin trade is based. The block chain assures that not only is every single transaction that ever takes place recorded, but that every single transaction is recorded on the computer of anyone who chooses to store the relevant information. Many, many users have complete records of every transaction in Bitcoins history readily available to them at any point, and anyone who wants in the information can obtain it with ease. These things make Bitcoin very hard to fool.

The Bitcoin network takes considerable processing power to run, and since those with the most processing power can make the most guesses, those who put the most power toward to sustaining the network earn the most currency. Each correct guess yields, at present, twenty-five Bitcoins, and as Bitcoins are presently worth something (although the value still fluctuates) every miner who earns any number of Bitcoins makes money. Some miners pull in Bitcoins on their own; and some also join or form pools wherein all who contribute earn a share of the profits.

Therefore, first answer is a vehement “yes” – not only can miners collude to get more money, Bitcoin is designed to encourage them to do so. Bitcoin pools are communal affairs, and there is nothing dishonest or underhanded about them.

Of course, the real question is:

;Can they do so in ways not sanctioned by Bitcoin network? Is there any way to rip off the network and make loads of money dishonestly?

Bitcoin isn't infallible. It can be cheated, but doing so is extremely difficult. Bitcoin was designed to evade some of the central problems with modern currencies – namely, that their trustworthiness hinges upon that of people who might not have users' best interests in mind. Every currency in the world (other than Bitcoin) is controlled by large institutions who keep track of what's done with it, and who can manipulate its value. And every other currency has value because people trust the institutions that control them.

Bitcoin doesn't ask that its users trust any institution. Its security is based on the cryptography that is an integral part of its structure, and that is readily available for any and all to see. Instead of one entity keeping track of transactions, the entire network does, so Bitcoins are astoundingly difficult to steal, or double-spend. Bitcoins are created in a regular and predictable fashion, and by many different users, so no one can decide to make a whole lot more and lessen their value. In short, Bitcoin is designed to be inflation-proof, double-spend-proof and completely distributed.

Nonetheless, there are a few ways that one can acquire Bitcoins dishonestly. Firstly, one can steal private keys. Key theft isn't something that Bitcoin security has been designed to prevent: it's up to users to keep their keys safe. But the cryptography is designed so that it is completely impossible to deduce someone's private key from their public one. As long as you keep your private key to yourself, you don't have much to worry about. Furthermore, one could theoretically create a new block chain, but due to the way in which the block chain is constructed, this would be extremely difficult and require massive amounts of processing power. A full explanation of the difficulties involved can be found in the [[block chain]] article.

Bitcoin can be ripped off – but doing so would be extremely hard and require considerable expertise and a staggering amount of processing power. And it's only going to get harder with time. Bitcoin isn't impenetrable, but it's close enough to put any real worries in the peripherals.

;Could miners fundamentally change the nature of Bitcoin?

Once again, almost certainly not.

Bitcoin is a distributed network, so any changes implemented to the system must be accepted by all users. Someone trying to change the way Bitcoins are generated would have to convince every user to download and use their software – so the only changes that would go through are those that would be equally benefit all users.

And thus, it is more or less impossible for anyone to change the function of Bitcoin to their advantage. If users don't like the changes, they won't adopt them, whereas if users do like them, then these will help everyone equally. Of course, one can conceive of a situation where someone manages to get a change pushed through that provides them with an advantage that no one notices, but given that Bitcoin is structurally relatively simple, it is unlikely that any major changes will go through without someone noticing first.

The fact that such changes are so difficult to make testifies to the fully distributed nature of Bitcoin. Any centrally controlled currency can be modified by its central agency without the consent of its adherents. Bitcoin has no central authority, so it changes only at the behest of the whole community. Bitcoins development represents a kind of collective evolution; the first of its kind among currencies.

==Help==
===I'd like to learn more. Where can I get help?===

* Read the [[Introduction|introduction to bitcoin]]
* See the videos, podcasts, and blog posts from the [[Press]]
* Read and post on the [[:Bitcoin:Community_portal#Bitcoin_Community_Forums|forums]]
* Chat on one of the [[:Bitcoin:Community_portal#IRC_Chat|Bitcoin IRC]] channels
* Listen to [http://omegataupodcast.net/2011/03/59-bitcoin-a-digital-decentralized-currency/ this podcast], which goes into the details of how bitcoin works
* Ask questions on the [http://bitcoin.stackexchange.com Bitcoin Stack Exchange]
* Use [http://wheretobuycryptocoins.com WhereToBuyCryptocoins]. It shows an cryptocurrency introduction, a getting started guide for beginners, also lists of markets, faucets, exchanges.

==See Also==

* [[Man page]]
* [[Introduction]]

[[de:FAQ]]
[[zh-cn:FAQ]]
[[fr:FAQ]]
[[ru:FAQ]]

[[Category:Technical]]
[[Category:Vocabulary]]

Help:FAQ

2014-09-02T13:39:06Z

DoctorBTC:

Here you will find answers to the most commonly asked questions.

== General ==
=== What is Bitcoin? ===
Bitcoin is a distributed peer-to-peer digital currency that can be transferred instantly and securely between any two people in the world. It's like electronic cash that you can use to pay friends or merchants.

=== What are bitcoins? ===
Bitcoins are the unit of currency of the Bitcoin system. A commonly used shorthand for this is “BTC” to refer to a price or amount (e.g. “100 BTC”).
There are such things as [[physical bitcoins]], but ultimately, a bitcoin is just a number associated with a [[Address|Bitcoin Address]]. A physical bitcoin is simply an object, such as a coin, with the number carefully embedded inside. See also an [[Introduction|easy intro]] to Bitcoin.

=== How can I get bitcoins? ===

There are a variety of ways to acquire bitcoins:
* You can buy bitcoins from [http://coinbase.com/?r=514b6eb6a18f2fdde50000db&utm_campaign=user-referral&src=referral-link Coinbase].
* Accept bitcoins as payment for goods or services.
* The most common way to buy bitcoins are the [[Buying bitcoins|Bitcoin Exchanges]]
* Visit [http://bitcoinx.io bitcoinx.io] for peer-to-peer ratings and reviews of bitcoin exchanges to see where to buy bitcoins
* Find someone to trade cash for bitcoins in-person through a [https://en.bitcoin.it/wiki/Category:Directories local directory].
* Participate in a [[Pooled mining|mining pool]].
* If you have a lot of mining hardware, you can solo mine and attempt to create a new [[block]] (currently yields 25 bitcoins plus transaction fees).
* Visit sites that provide [[Trade#Free_Samples_and_Offers|free samples and offers]].

===Does Bitcoin guarantee an influx of free money?===

Since Bitcoin is a new technology, what it is and how it works may be initially unclear. Bitcoin is sometimes presented as being one of three things:
<ol style="list-style-type: upper-alpha;">
<li>Some sort of online 'get-rich-quick' scam.</li>
<li>A loophole in the market economy, the installation of which guarantees a steady influx of cash.</li>
<li>A sure investment that will almost certainly yield a profit.</li>
</ol>
In fact, none of the above are true. Let's look at them independently.

;Is Bitcoin a 'get-rich-quick' scheme?
:If you've spent much time on the Internet, you've probably seen ads for many 'get-rich-quick' schemes. These ads usually promise huge profits for a small amounts of easy work. Such schemes are usually pyramid/matrix-style schemes that make money from their own employees and offer nothing of any real value. Most convince one to buy packages that will make them earn hundreds a day, which in fact have the buyer distribute more such ads, and make minute profits.

:Bitcoin is in no way similar to these schemes. Bitcoin doesn't promise windfall profits. There is no way for the developers to make money from your involvement or to take money from you. That bitcoins are nearly impossible to acquire without the owner's consent represents one of its greatest strengths. Bitcoin is an experimental, virtual currency that may succeed or may fail. None of its developers expect to get rich off of it.

:A more detailed answer to this question can be found [http://bitcointalk.org/?topic=7815.0 here].

;Will I make money by installing the client?
:Most people who use Bitcoin don't earn anything by doing so, and the default client has no built-in way to earn Bitcoins. A small minority of people with dedicated, high-performance hardware do earn some Bitcoins by "''mining''" (generating new bitcoins, see [[#What is mining?|What is mining?]]) with special software, but joining Bitcoin shouldn't be construed as being the road to riches. Most Bitcoin users get involved because they find the project conceptually interesting and don't earn anything by doing so. This is also why you won't find much speculation about the political or economic repercussions of Bitcoin anywhere on this site: Bitcoin developers owe their dedication to the project's intellectual yieldings more than to those of a monetary nature. Bitcoin is still taking its first baby steps; it may go on to do great things but right now it only has something to offer those chasing conceptually interesting projects or bleeding edge technology.

;As an investment, is Bitcoin a sure thing?
:Bitcoin is a new and interesting electronic currency, the value of which is not backed by any single government or organization. Like other currencies, it is worth something partly because people are willing to trade it for goods and services. Its exchange rate fluctuates continuously, and sometimes wildly. It lacks wide acceptance and is vulnerable to manipulation by parties with modest funding. Security incidents such as website and account compromise may trigger major sell-offs. Other fluctuations can build into positive feedback loops and cause much larger exchange rate fluctuations. Anyone who puts money into Bitcoin should understand the risk they are taking and consider it a high-risk currency. Later, as Bitcoin becomes better known and more widely accepted, it may stabilize, but for the time being it is unpredictable. Any investment in Bitcoin should be done carefully and with a clear plan to manage the risk.

=== Can I buy bitcoins with Paypal? ===

It is possible to buy [[physical bitcoins]] with PayPal but it is otherwise difficult and/or expensive to do so for non-physical bitcoins, because of significant risk to the seller.

There is a [https://www.virwox.com workaround] that can be done in order to use Paypal to buy Bitcoins but it holds within it higher transaction fees. Using the [https://www.virwox.com Virtual World Exchange] you can buy Second Life Lindens (SLL) with Paypal and then convert your SLL to Bitcoins. This process will charge you transaction fees of around 6% but will let you purchase Bitcoins pretty quickly as opposed to a wire transfer. The reason this method works is because you do not buy Bitcoins with Paypal directly, you only buy SLL with Paypal (which is acceptable by Paypal's TOS) and then exchange your SLL to Bitcoin.

While it is possible to find an individual who wishes to sell Bitcoin to you via Paypal, (perhaps via [http://www.bitcoin-otc.com/ #bitcoin-otc] ) most exchanges do not allow funding through PayPal. This is due to repeated cases where someone pays for bitcoins with Paypal, receives their bitcoins, and then fraudulently complains to Paypal that they never received their purchase. PayPal often sides with the fraudulent buyer in this case, which means any seller needs to cover that risk with higher fees or refuse to accept PayPal altogether.

Buying Bitcoins from individuals this way is still possible, but requires the seller to have some trust that the buyer will not file a claim with PayPal to reverse the payment.

=== Where can I find a forum to discuss Bitcoin? ===

Please visit the [[Bitcoin:Community_portal#Bitcoin_Community_Forums_on_various_platforms|Community Portal]] for links to Bitcoin-related forums.

=== How are new bitcoins created? ===

New bitcoins are generated by the network through the process of "[[#What is mining?|''mining'']]". In a process that is similar to a continuous raffle draw, mining nodes on the network are awarded bitcoins each time they find the solution to a certain mathematical problem (and thereby create a new [[block]]). Creating a block is a [[proof of work]] with a difficulty that varies with the overall strength of the network. The reward for solving a block is [[Controlled Currency Supply|automatically adjusted]] so that, ideally, every four years of operation of the Bitcoin network, half the amount of bitcoins created in the prior 4 years are created. A maximum of {{formatnum:10499889.80231183}} bitcoins were created in the first 4 (approx.) years from January 2009 to November 2012. Every four years thereafter this amount halves, so it should be {{formatnum:5250000}} over years 4-8, {{formatnum:2625000}} over years 8-12, and so on. Thus the total number of bitcoins in existence can never exceed {{formatnum:20999839.77085749}} and counting. See [[Controlled Currency Supply]].

Blocks are [[Mining|mined]] every 10 minutes, on average and for the first four years ({{formatnum:210000}} blocks) each block included 50 new bitcoins. As the amount of processing power directed at mining changes, the difficulty of creating new bitcoins changes. This difficulty factor is calculated every 2016 blocks and is based upon the time taken to generate the previous 2016 blocks. See [[Mining]].

=== What's the current total number of bitcoins in existence? ===

[http://blockexplorer.com/q/totalbc Current count]. Also see [https://blockchain.info/charts/total-bitcoins Total bitcoins in circulation chart]

The number of blocks times the coin value of a block is the number of coins in existence. The coin value of a block is 50 BTC for each of the first {{formatnum:210000}} blocks, 25 BTC for the next {{formatnum:210000}} blocks, then 12.5 BTC, 6.25 BTC and so on.

=== How divisible are bitcoins? ===

A bitcoin can be divided down to 8 decimal places. Therefore, 0.00000001 BTC is the smallest amount that can be handled in a transaction. If necessary, the protocol and related software can be modified to handle even smaller amounts.

=== What do I call the various denominations of bitcoin? ===

There is a lot of discussion about the naming of these fractions of bitcoins. The leading candidates are:

* 1 BTC = 1 bitcoin
* 0.01 BTC = 1 cBTC = 1 centibitcoin (also referred to as bitcent)
* 0.001 BTC = 1 mBTC = 1 millibitcoin (also referred to as mbit (pronounced em-bit) or millibit or even bitmill)
* 0.000 001 BTC = 1 μBTC = 1 microbitcoin (also referred to as ubit (pronounced yu-bit) or microbit)

The above follows the accepted international SI prefixes for hundredths, thousandths, and millionths. There are many arguments against the special case of 0.01 BTC since it is unlikely to represent anything meaningful as the Bitcoin economy grows (it certainly won't be the equivalent of 0.01 USD, GBP or EUR). Equally, the inclusion of existing national currency denominations such as "cent", "nickel", "dime", "pence", "pound", "kopek" and so on are to be discouraged; this is a worldwide currency.

One exception is the "satoshi" which is smallest denomination currently possible

* 0.000 000 01 BTC = 1 satoshi (pronounced sa-toh-shee)
which is so named in honour of Satoshi Nakamoto, the pseudonym of the inventor of Bitcoin.

For an overview of all defined units of Bitcoin (including less common and niche units), see [[Units]].

Further discussion on this topic can be found on the forums here:

* [https://bitcointalk.org/index.php?topic=14438.msg195287#msg195287 We need names]
* [https://bitcointalk.org/index.php?topic=8282.0 What to call 0.001 BTC]

=== How does the halving work when the number gets really small? ===

Eventually the reward will go from 0.00000001 BTC to zero and no more bitcoins will be created.

The block reward calculation is done as a right bitwise shift of a 64-bit signed integer, which means it is divided by two and rounded down. The integer is equal to the value in BTC * 100,000,000 since internally in the reference client software, all Bitcoin balances and values are stored as unsigned integers.

With an initial block reward of 50 BTC, it will take many 4-year periods for the block reward to reach zero.

=== How long will it take to generate all the coins? ===

The last block that will generate coins will be block #6,929,999 which should be generated at or near the year 2140. The total number of coins in circulation will then remain static at 20,999,999.9769 BTC.

Even if the allowed precision is expanded from the current 8 decimals, the total BTC in circulation will always be slightly below 21 million (assuming everything else stays the same). For example, with 16 decimals of precision, the end total would be 20,999,999.999999999496 BTC.

=== If no more coins are going to be generated, will more blocks be created? ===

Absolutely! Even before the creation of coins ends, the use of [[transaction fee|transaction fees]] will likely make creating new blocks more valuable from the fees than the new coins being created. When coin generation ends, these fees will sustain the ability to use bitcoins and the Bitcoin network. There is no practical limit on the number of blocks that will be mined in the future.

=== But if no more coins are generated, what happens when Bitcoins are lost? Won't that be a problem? ===

Because of the law of supply and demand, when fewer bitcoins are available the ones that are left will be in higher demand, and therefore will have a higher value. So, as Bitcoins are lost, the remaining bitcoins will eventually increase in value to compensate. As the value of a bitcoin increases, the number of bitcoins required to purchase an item '''de'''creases. This is a [[Deflationary spiral|deflationary economic model]]. As the average transaction size reduces, transactions will probably be denominated in sub-units of a bitcoin such as millibitcoins ("Millies") or microbitcoins ("Mikes").

The Bitcoin protocol uses a base unit of one hundred-millionth of a Bitcoin ("a Satoshi"), but unused bits are available in the protocol fields that could be used to denote even smaller subdivisions.

=== If every transaction is broadcast via the network, does Bitcoin scale? ===
The Bitcoin protocol allows lightweight clients that can use Bitcoin without downloading the entire transaction history. As traffic grows and this becomes more critical, implementations of the concept will be developed. Full network nodes will at some point become a more specialized service.

With some modifications to the software, full Bitcoin nodes could easily keep up with both VISA and MasterCard combined, using only fairly modest hardware (a single high end server by todays standards). It is worth noting that the MasterCard network is structured somewhat like Bitcoin itself - as a peer to peer broadcast network.

Learn more about [[Scalability]].

==Economy==
=== Where does the value of Bitcoin stem from? What backs up Bitcoin? ===
Bitcoins have value because they are useful and because they are [[Controlled Currency Supply|scarce]]. As they are accepted by more merchants, their value will [http://en.wikipedia.org/wiki/Sticky_%28economics%29 stabilize]. See the [[Trade|list of Bitcoin-accepting sites]].

When we say that a currency is backed up by gold, we mean that there's a promise in place that you can exchange the currency for gold. Bitcoins, like dollars and euros, are not backed up by anything except the variety of merchants that accept them.

It's a common misconception that Bitcoins gain their value from the cost of electricity required to generate them. Cost doesn't equal value – hiring 1,000 men to shovel a big hole in the ground may be costly, but not valuable. Also, even though scarcity is a critical requirement for a useful currency, it alone doesn't make anything valuable. For example, your fingerprints are scarce, but that doesn't mean they have any exchange value.

Alternatively it needs to be added that while the law of supply and demand applies it does not guarantee value of Bitcoins in the future. If confidence in Bitcoins is lost then it will not matter that the supply can no longer be increased, the demand will fall off with all holders trying to get rid of their coins. An example of this can be seen in cases of state currencies, in cases when the state in question dissolves and so no new supply of the currency is available (the central authority managing the supply is gone), however the demand for the currency falls sharply because confidence in its purchasing power disappears. Of-course Bitcoins do not have such central authority managing the supply of the coins, but it does not prevent confidence from eroding due to other situations that are not necessarily predictable.

=== Is Bitcoin a bubble? ===
Yes, in the same way as the euro and dollar are. They only have value in exchange and have no inherent value. If everyone suddenly stopped accepting your dollars, euros or bitcoins, the "bubble" would burst and their value would drop to zero. But that is unlikely to happen: even in Somalia, where the government collapsed 20 years ago, [http://en.wikipedia.org/wiki/Somali_shilling Somali shillings] are still accepted as payment.

=== Is Bitcoin a Ponzi scheme? ===
In a Ponzi Scheme, the founders persuade investors that they’ll profit. Bitcoin does not make such a guarantee. There is no central entity, just individuals building an economy.

A ponzi scheme is a zero sum game. Early adopters can only profit at the expense of late adopters. Bitcoin has possible win-win outcomes. Early adopters profit from the rise in value. Late adopters, and indeed, society as a whole, benefit from the usefulness of a stable, fast, inexpensive, and widely accepted p2p currency.

The fact that early adopters benefit more doesn't alone make anything a Ponzi scheme. All good investments in successful companies have this quality.

=== Doesn't Bitcoin unfairly benefit early adopters? ===
Early adopters in Bitcoin are taking a risk and invested resources in an unproven technology. By so doing, they help Bitcoin become what it is now and what it will be in the future (hopefully, a ubiquitous decentralized digital currency). It is only fair they will reap the benefits of their successful investment.

In any case, any bitcoin generated will probably change hands dozens of time as a medium of exchange, so the profit made from the initial distribution will be insignificant compared to the total commerce enabled by Bitcoin. Many of the earliest users of Bitcoin have traded their coins at valuations below $1 US, or other amounts which are small compared to contemporary prices.

===Won't loss of wallets and the finite amount of Bitcoins create excessive deflation, destroying Bitcoin? ===
Worries about Bitcoin being destroyed by deflation are not entirely unfounded. Unlike most currencies, which experience inflation as their founding institutions create more and more units, Bitcoin will likely experience gradual deflation with the passage of time. Bitcoin is unique in that only a small amount of units will ever be produced (twenty-one million to be exact), this number has been known since the project's inception, and the units are created at a predictable rate.

Also, Bitcoin users are faced with a danger that doesn't threaten users of any other currency: if a Bitcoin user loses his wallet, his money is gone forever, unless he finds it again. And not just to him; it's gone completely out of circulation, rendered utterly inaccessible to anyone. As people will lose their wallets, the total number of Bitcoins will slowly decrease.

Therefore, Bitcoin seems to be faced with a unique problem. Whereas most currencies inflate over time, Bitcoin will mostly likely do just the opposite. Time will see the irretrievable loss of an ever-increasing number of Bitcoins. An already small number will be permanently whittled down further and further. And as there become fewer and fewer Bitcoins, the laws of supply and demand suggest that their value will probably continually rise.

Thus Bitcoin is bound to once again stray into mysterious territory, because no one exactly knows what happens to a currency that grows continually more valuable. Many economists claim that a low level of inflation is a good thing for a currency, but nobody is quite sure about what might happens to one that continually deflates. Although deflation could hardly be called a rare phenomenon, steady, constant deflation is unheard of. There may be a lot of speculation, but no one has any hard data to back up their claims.

That being said, there is a mechanism in place to combat the obvious consequences. Extreme deflation would render most currencies highly impractical: if a single Canadian dollar could suddenly buy the holder a car, how would one go about buying bread or candy? Even pennies would fetch more than a person could carry. Bitcoin, however, offers a simple and stylish solution: infinite divisibility. Bitcoins can be divided up and trade into as small of pieces as one wants, so no matter how valuable Bitcoins become, one can trade them in practical quantities.

In fact, infinite divisibility should allow Bitcoins to function in cases of extreme wallet loss. Even if, in the far future, so many people have lost their wallets that only a single Bitcoin, or a fraction of one, remains, Bitcoin should continue to function just fine. No one can claim to be sure what is going to happen, but deflation may prove to present a smaller threat than many expect.

For more information, see the [[Deflationary spiral]] page.

=== What if someone bought up all the existing Bitcoins? ===
Bitcoin markets are competitive -- meaning the price of a bitcoin will rise or fall depending on supply and demand at certain price levels. Only a fraction of bitcoins issued to date are found on the exchange markets for sale. So even though technically, a buyer with lots of money could buy all the bitcoins offered for sale, unless those holding the rest of the bitcoins offer them for sale as well, even the wealthiest, most determined buyer can't get at them.

Additionally, new currency continues to be issued daily and will continue to do so for decades; though over time the rate at which they are issued declines to insignificant levels. Those who are mining aren't obligated to sell their bitcoins so not all bitcoins will make it to the markets even.

This situation doesn't suggest, however, that the markets aren't vulnerable to price manipulation. It doesn't take significant amounts of money to move the market price up or down, and thus Bitcoin remains a volatile asset.

===What if someone creates a new block chain, or a new digital currency that renders Bitcoin obsolete?===

That the block chain cannot be easily forked represents one of the central security mechanisms of Bitcoin. Given the choice between two block chains, a Bitcoin miner always chooses the longer one - that is to say, the one with the more complex hash. Thusly, it ensures that each user can only spend their bitcoins once, and that no user gets ripped off.

As a consequence of the block chain structure, there may at any time be many different sub-branches, and the possibility always exists of a transaction being over-written by the longest branch, if it has been recorded in a shorter one. The older a transaction is though, the lower its chances of being over-written, and the higher of becoming permanent. Although the block chain prevents one from spending more Bitcoins than one has, it means that transactions can be accidentally nullified.

A new block chain would leave the network vulnerable to [[double-spending|double-spend]] attacks. However, the creation of a viable new chain presents considerable difficulty, and the possibility does not present much of a risk.

Bitcoin will always choose the longer Block Chain and determines the relative length of two branches by the complexities of their hashes. Since the hash of each new block is made from that of the block preceding it, to create a block with a more complex hash, one must be prepared to do more computation than has been done by the entire Bitcoin network from the fork point up to the newest of the blocks one is trying to supersede. Needless to say, such an undertaking would require a very large amount of processing power and since Bitcoin is continually growing and expanding, it will likely only require more with the passage of time.

A much more distinct and real threat to the Bitcoin use is the development of other, superior virtual currencies, which could supplant Bitcoin and render it obsolete and valueless.

A great deal of careful thought and ingenuity has gone into the development of Bitcoin, but it is the first of its breed, a prototype, and vulnerable to more highly-evolved competitors. At present, any threatening rivals have yet to rear their heads; Bitcoin remains the first and foremost private virtual currency, but we can offer no guarantees that it will retain that position. It would certainly be in keeping with internet history for a similar system built from the same principles to supersede and cast Bitcoin into obsolescence, after time had revealed its major shortcomings. Friendster and Myspace suffered similar fates at the hand of Facebook, Napster was ousted by Limeware, Bearshare and torrent applications, and Skype has all but crushed the last few disciples of the Microsoft Messenger army.

This may sound rather foreboding, so bear in mind that the introduction of new and possibly better virtual currencies will not necessarily herald Bitcoin's demise. If Bitcoin establishes itself sufficiently firmly before the inception of the next generation of private, online currencies so as to gain widespread acceptance and general stability, future currencies may pose little threat even if they can claim superior design. This is known as the network effect.

=== Is Bitcoin open to value manipulation? ===

The current low market cap of Bitcoin means that any investor with deep enough pockets can significantly change/manipulate the rate. Is this a problem?

This is only a problem if you are investing in Bitcoin for short period of time. A manipulator can't change the fundamentals, and over a period of 5-10 years, the fundamentals will win over any short term manipulations.

==Sending and Receiving Payments==

=== Why do I have to wait 10 minutes before I can spend money I received? ===

10 minutes is the average time taken to find a block. It can be significantly more or less time than that depending on luck; 10 minutes is simply the average case.

[[Blocks]] (shown as "confirmations" in the GUI) are how the Bitcoin achieves consensus on who owns what. Once a block is found everyone agrees that you now own those coins, so you can spend them again. Until then it's possible that some network nodes believe otherwise, if somebody is attempting to defraud the system by reversing a transaction. The more confirmations a transaction has, the less risk there is of a reversal. Only 6 blocks or 1 hour is enough to make reversal computationally impractical. This is dramatically better than credit cards which can see chargebacks occur up to three months after the original transaction!

Ten minutes was specifically chosen by [[Satoshi]] as a tradeoff between first confirmation time and the amount of work wasted due to chain splits. After a block is mined, it takes time for other miners to find out about it, and until then they are actually competing against the new block instead of adding to it. If someone mines another new block based on the old block chain, the network can only accept one of the two, and all the work that went into the other block gets wasted. For example, if it takes miners 1 minute on average to learn about new blocks, and new blocks come every 10 minutes, then the overall network is wasting about 10% of its work. Lengthening the time between blocks reduces this waste.

As a thought experiment, what if the Bitcoin network grew to include Mars? From the farthest points in their orbits, it takes about 20 minutes for a signal to travel from Earth to Mars. With only 10 minutes between new blocks, miners on Mars would always be 2 blocks behind the miners on Earth. It would be almost impossible for them to contribute to the block chain. If we wanted collaborate with those kinds of delays, we would need at least a few hours between new blocks.

[[File:TransactionConfirmationTimesExample.PNG]]

=== Do you have to wait until my transactions are confirmed in order to buy or sell things with Bitcoin? ===

YES, you do, IF the transaction is non-recourse. The Bitcoin reference software does not display transactions as confirmed until six blocks have passed (confirmations). As transactions are buried in the chain they become increasingly non-reversible but are very reversible before the first confirmation. Two to six confirmations are recommended for non-recourse situations depending on the value of the transactions involved.

When people ask this question they are usually thinking about applications like supermarkets. This generally is a recourse situation: if somebody tries to double-spend on a face-to-face transaction it might work a few times, but probabalistically speaking eventually one of the double-spends will get noticed, and the penalty for shoplifting charges in most localities is calibrated to be several times worse than the proceeds of a single shoplifting event.

Double-spends might be a concern for something like a snack machine in a low-traffic area with no nearby security cameras. Such a machine shouldn't honor zero-confirmation payments, and should instead use some other mechanism of clearing Bitcoin or validating transactions against reversal, see the wiki article [[Myths#Point_of_sale_with_bitcoins_isn.27t_possible_because_of_the_10_minute_wait_for_confirmation|here]] for alternatives.

Applications that require immediate payment processing, like supermarkets or snack machines, need to manage the risks. Here is one way to reverse an unconfirmed payment:

A [[Double-spending#Finney_attack|Finney attack]] is where an attacker mines a block containing a movement of some coins back to themselves. Once they find a block solution, they quickly go to a merchant and make a purchase, then broadcast the block, thus taking back the coins. This attack is a risk primarily for goods that are dispatched immediately, like song downloads or currency trades. Because the attacker can't choose the time of the attack, it isn't a risk for merchants such as supermarkets where you can't choose exactly when to pay (due to queues, etc). The attack can fail if somebody else finds a block containing the purchasing transaction before you release your own block, therefore, merchants can reduce but not eliminate the risk by making purchasers wait some length of time that's less than a confirm.

Because pulling off this attack is not trivial, merchants who need to sell things automatically and instantly are most likely to adjust the price to include the cost of reversal fraud, or elect to use special insurance.

=== I was sent some bitcoins and they haven't arrived yet! Where are they? ===

Don't panic! There are a number of reasons why your bitcoins might not show up yet, and a number of ways to diagnose them.

The latest version of the Bitcoin-Qt client tells you how far it has yet to go in downloading the blockchain. Hover over the icon in the bottom right corner of the client to learn your client's status.

If it has not caught up then it's possible that your transaction hasn't been included in a block yet.

You can check pending transactions in the network by going [https://www.biteasy.com here] or [http://blockchain.info here] and then searching for your address. If the transaction is listed here then it's a matter of waiting until it gets included in a block before it will show in your client.

If the transaction is based on a coin that was in a recent transaction then it could be considered a low priority transaction. Transfers can take longer if the transaction fee paid was not high enough. If there is no fee at all the transfer can get a very low priority and take hours or even days to be included in a block.

=== Why does my Bitcoin address keep changing? ===

Unlike postal or email addresses, Bitcoin addresses are single-use.
This means that whenever you want to receive a payment, you need to generate a new address.

While it is technically possible to receive coins multiple times with a single address, this compromises your wallet's security as well as the privacy of the entire Bitcoin network, and also makes it impossible to know for certain who sent the coins or why.

===How much will the transaction fee be?===

Some transactions might require a [[transaction fee]] for them to get confirmed in a timely manner. The transaction fee is processed by and received by the bitcoin miner. The most recent version of the Bitcoin client will estimate an appropriate fee when a fee might be required.

The fee is added to the payment amount. For example, if you are sending a 1.234 BTC payment and the client requires a 0.0005 BTC fee, then 1.2345 BTC will be subtracted from the wallet balance for the entire transaction and the address for where the payment was sent will receive a payment of 1.234 BTC.

A fee might be imposed because your transaction looks like a denial of service attack to the Bitcoin system. For example, it might be burdensome to transmit or it might recycle Bitcoins you recently received. The wallet software attempts to avoid generating burdensome transactions, but it isn't always able to do so: The funds in your wallet might be new or composed of many tiny payments.

Because the fee is related to the amount of data that makes up the transaction and not to the amount of Bitcoins being sent, the fee may seem extremely low (0.0005 BTC for a 1,000 BTC transfer) or unfairly high (0.004 BTC for a 0.02 BTC payment, or about 20%). If you are receiving tiny amounts (''e.g.'' as small payments from a mining pool) then fees when sending will be higher than if your activity follows the pattern of conventional consumer or business transactions.

As of Bitcoin 0.5.3 the required fee will not be higher than 0.05 BTC. For most users there is usually no required fee at all. If a fee is required it will most commonly be 0.0005 BTC.

=== What happens when someone sends me a bitcoin but my computer is powered off? ===

Bitcoins are not actually "sent" to your wallet; the software only uses that term so that we can use the currency without having to learn new concepts. Your wallet is only needed when you wish to spend coins that you've received.

If you are sent coins when your wallet client program is not running, and you later launch the wallet client program, the coins will eventually appear as if they were just received in the wallet. That is to say, when the client program is started it must download blocks and catch up with any transactions it did not already know about.

=== How long does "synchronizing" take when the Bitcoin client is first installed? What's it doing? ===

The popular Bitcoin client software from bitcoin.org implements a "full" Bitcoin node: It can carry out all the duties of the Bitcoin P2P system, it isn't simply a "client". One of the principles behind the operation of full Bitcoin nodes is that they don't assume that the other participants have followed the rules of the Bitcoin system. During synchronization, the software is processing historical Bitcoin transactions and making sure for itself that all of the rules of the system have been correctly followed.

In normal operation, after synchronizing, the software should use a hardly noticeable amount of your computer's resources.

When the wallet client program is first installed, its initial validation requires a lot of work from your computer's hard disk, so the amount of time to synchronize depends on your disk speed and, to a lesser extent, your CPU speed. It can take anywhere from a few hours to a day or so. On a slow computer it could take more than 40 hours of continuous synchronization, so check your computer's power-saving settings to ensure that it does not turn its hard disk off when unattended for a few hours. You can use the Bitcoin software during synchronization, but you may not see recent payments to you until the client program has caught up to the point where those transactions happened.

If you feel that this process takes too long, you can download a pre-synchronized blockchain from [http://eu2.bitcoincharts.com/blockchain/ http://eu2.bitcoincharts.com/blockchain/]. Alternatively, you can try an alternative "lite" client such as Multibit or a super-light client like electrum, though these clients have somewhat weaker security, are less mature, and don't contribute to the health of the P2P network.

==Networking==
=== Do I need to configure my firewall to run Bitcoin? ===

Bitcoin will connect to other nodes, usually on TCP port 8333. You will need to allow outgoing TCP connections to port 8333 if you want to allow your Bitcoin client to connect to many nodes. [[Testnet]] uses TCP port 18333 instead of 8333.

If you want to restrict your firewall rules to a few IPs, you can find stable nodes in the [[Fallback Nodes|fallback nodes list]].

=== How does the peer finding mechanism work? ===

Bitcoin finds peers primarily by forwarding peer announcements within its own network and each node saves a database of peers that it's aware of, for future use. In order to bootstrap this process Bitcoin needs a list of initial peers, these can be provided manually but normally it obtains them by querying a set of DNS domain names which have automatically updated lists, if that doesn't work it falls back to a built-in list which is updated from time to time in new versions of the software. In the reference software initial peers can also be specified manually by adding an addr.txt to the data directory or via the addnode parameter.

==Mining==
===What is mining?===
[[Mining]] is the process of spending computation power to secure Bitcoin transactions against reversal and introducing new Bitcoins to the system.

Technically speaking, mining is the calculation of a [[hash]] of the a block header, which includes among other things a reference to the previous block, a hash of a set of transactions and a [[nonce]]. If the hash value is found to be less than the current [[target]] (which is inversely proportional to the [[difficulty]]), a new block is formed and the miner gets the newly generated Bitcoins (25 per block at current levels). If the hash is not less than the current target, a new nonce is tried, and a new hash is calculated. This is done millions of times per second by each miner.

===Is mining used for some useful computation?===
The computations done when mining are internal to Bitcoin and not related to any other distributed computing projects. They serve the purpose of securing the Bitcoin network, which is useful.

===Is it not a waste of energy?===
Spending energy on creating and securing a free monetary system is hardly a waste. Also, services necessary for the operation of currently widespread monetary systems, such as banks and credit card companies, also spend energy, arguably more than Bitcoin would.

===Why don't we use calculations that are also useful for some other purpose?===
To provide security for the Bitcoin network, the calculations involved need to have some [http://bitcoin.stackexchange.com/questions/5617/why-are-bitcoin-calculation-useless/5618#5618 very specific features]. These features are incompatible with leveraging the computation for other purposes.

===How can we stop miners from creating zero transaction blocks?===
The incentive for miners to include transactions is in the fees that come along with them. If we were to implement some minimum number of transactions per block it would be trivial for a miner to create and include transactions merely to surpass that threshold. As the network matures, the block reward drops, and miners become more dependent on transactions fees to pay their costs, the problem of zero transaction blocks should diminish over time.

===How does the proof-of-work system help secure Bitcoin?===
Bitcoin uses the [[Hashcash]] proof of work with a minor adaption. To give a general idea of the mining process, imagine this setup:

payload = <some data related to things happening on the Bitcoin network>
nonce = 1
hash = [http://en.wikipedia.org/wiki/SHA2 SHA2]( [http://en.wikipedia.org/wiki/SHA2 SHA2]( payload + nonce ) )

The work performed by a miner consists of repeatedly increasing "nonce" until
the hash function yields a value, that has the rare property of being below a certain
target threshold. (In other words: The hash "starts with a certain number of zeroes",
if you display it in the fixed-length representation, that is typically used.)

As can be seen, the mining process doesn't compute anything special. It merely
tries to find a number (also referred to as nonce) which - in combination with the payload -
results in a hash with special properties.

The advantage of using such a mechanism consists of the fact, that it is very easy to check a result: Given the payload and a specific nonce, only a single call of the hashing function is needed to verify that the hash has the required properties. Since there is no known way to find these hashes other than brute force, this can be used as a "proof of work" that someone invested a lot of computing power to find the correct nonce for this payload.

This feature is then used in the Bitcoin network to secure various aspects. An attacker
that wants to introduce malicious payload data into the network, will need to do the
required proof of work before it will be accepted. And as long as honest miners have more
computing power, they can always outpace an attacker.

Also see [http://en.wikipedia.org/wiki/Hashcash Hashcash] and [http://en.wikipedia.org/wiki/Proof-of-work_system Proof-of-work system] and [http://en.wikipedia.org/wiki/SHA2 SHA2] and on Wikipedia.

===Why was the "Generate coin" option of the client software removed?===

The option wasn't removed, but it is now only accessible via the command-line or the configuration file. The reason for this is that many users were complaining after they turned on and expecting to receive coins. Without specialized mining hardware a user is exceptionally unlikely generate a block on their own at the network's current [[difficulty|security level]].

==Security==

===Could miners collude to give themselves money or to fundamentally change the nature of Bitcoin?===

There are two questions in here. Let's look at them separately.

;Could miners gang up and give themselves money?

Mining itself is the process of creating new blocks in the block chain. Each block contains a list of all the transactions that have taken place across the entire Bitcoin network since the last block was created, as well as a hash of the previous block. New blocks are 'mined', or rather, generated, by Bitcoin clients correctly guessing sequences of characters in codes called 'hashes,' which are created using information from previous blocks. Bitcoin users may download specialized 'mining' software, which allows them to dedicate some amount of their processing power – however large or small – to guessing at strings within the hash of the previous block. Whoever makes the right guess first, thus creating a new block, receives a reward in Bitcoins.

The block chain is one of the two structures that makes Bitcoin secure, the other being the public-key encryption system on which Bitcoin trade is based. The block chain assures that not only is every single transaction that ever takes place recorded, but that every single transaction is recorded on the computer of anyone who chooses to store the relevant information. Many, many users have complete records of every transaction in Bitcoins history readily available to them at any point, and anyone who wants in the information can obtain it with ease. These things make Bitcoin very hard to fool.

The Bitcoin network takes considerable processing power to run, and since those with the most processing power can make the most guesses, those who put the most power toward to sustaining the network earn the most currency. Each correct guess yields, at present, twenty-five Bitcoins, and as Bitcoins are presently worth something (although the value still fluctuates) every miner who earns any number of Bitcoins makes money. Some miners pull in Bitcoins on their own; and some also join or form pools wherein all who contribute earn a share of the profits.

Therefore, first answer is a vehement “yes” – not only can miners collude to get more money, Bitcoin is designed to encourage them to do so. Bitcoin pools are communal affairs, and there is nothing dishonest or underhanded about them.

Of course, the real question is:

;Can they do so in ways not sanctioned by Bitcoin network? Is there any way to rip off the network and make loads of money dishonestly?

Bitcoin isn't infallible. It can be cheated, but doing so is extremely difficult. Bitcoin was designed to evade some of the central problems with modern currencies – namely, that their trustworthiness hinges upon that of people who might not have users' best interests in mind. Every currency in the world (other than Bitcoin) is controlled by large institutions who keep track of what's done with it, and who can manipulate its value. And every other currency has value because people trust the institutions that control them.

Bitcoin doesn't ask that its users trust any institution. Its security is based on the cryptography that is an integral part of its structure, and that is readily available for any and all to see. Instead of one entity keeping track of transactions, the entire network does, so Bitcoins are astoundingly difficult to steal, or double-spend. Bitcoins are created in a regular and predictable fashion, and by many different users, so no one can decide to make a whole lot more and lessen their value. In short, Bitcoin is designed to be inflation-proof, double-spend-proof and completely distributed.

Nonetheless, there are a few ways that one can acquire Bitcoins dishonestly. Firstly, one can steal private keys. Key theft isn't something that Bitcoin security has been designed to prevent: it's up to users to keep their keys safe. But the cryptography is designed so that it is completely impossible to deduce someone's private key from their public one. As long as you keep your private key to yourself, you don't have much to worry about. Furthermore, one could theoretically create a new block chain, but due to the way in which the block chain is constructed, this would be extremely difficult and require massive amounts of processing power. A full explanation of the difficulties involved can be found in the [[block chain]] article.

Bitcoin can be ripped off – but doing so would be extremely hard and require considerable expertise and a staggering amount of processing power. And it's only going to get harder with time. Bitcoin isn't impenetrable, but it's close enough to put any real worries in the peripherals.

;Could miners fundamentally change the nature of Bitcoin?

Once again, almost certainly not.

Bitcoin is a distributed network, so any changes implemented to the system must be accepted by all users. Someone trying to change the way Bitcoins are generated would have to convince every user to download and use their software – so the only changes that would go through are those that would be equally benefit all users.

And thus, it is more or less impossible for anyone to change the function of Bitcoin to their advantage. If users don't like the changes, they won't adopt them, whereas if users do like them, then these will help everyone equally. Of course, one can conceive of a situation where someone manages to get a change pushed through that provides them with an advantage that no one notices, but given that Bitcoin is structurally relatively simple, it is unlikely that any major changes will go through without someone noticing first.

The fact that such changes are so difficult to make testifies to the fully distributed nature of Bitcoin. Any centrally controlled currency can be modified by its central agency without the consent of its adherents. Bitcoin has no central authority, so it changes only at the behest of the whole community. Bitcoins development represents a kind of collective evolution; the first of its kind among currencies.

==Help==
===I'd like to learn more. Where can I get help?===

* Read the [[Introduction|introduction to bitcoin]]
* See the videos, podcasts, and blog posts from the [[Press]]
* Read and post on the [[:Bitcoin:Community_portal#Bitcoin_Community_Forums|forums]]
* Chat on one of the [[:Bitcoin:Community_portal#IRC_Chat|Bitcoin IRC]] channels
* Listen to [http://omegataupodcast.net/2011/03/59-bitcoin-a-digital-decentralized-currency/ this podcast], which goes into the details of how bitcoin works
* Ask questions on the [http://bitcoin.stackexchange.com Bitcoin Stack Exchange]
* Use [http://wheretobuycryptocoins.com WhereToBuyCryptocoins]. It shows an cryptocurrency introduction, a getting started guide for beginners, also lists of markets, faucets, exchanges.

==See Also==

* [[Man page]]
* [[Introduction]]

[[de:FAQ]]
[[zh-cn:FAQ]]
[[fr:FAQ]]
[[ru:FAQ]]

[[Category:Technical]]
[[Category:Vocabulary]]

Help:Introduction

2014-08-15T02:16:10Z

DoctorBTC:

The purpose of this page is to provide a general overview of the Bitcoin system and economy.

==Basic Concepts==

===Currency===

Alice wants to buy the [http://www.grasshillalpacas.com/alpacaproductsforbitcoinoffer.html Alpaca socks] which Bob has for sale. In return, she must provide something of equal value to Bob. The most efficient way to do this is by using a medium of exchange that Bob accepts which would be classified as currency. Currency makes trade easier by eliminating the need for [http://en.wikipedia.org/wiki/Coincidence_of_wants coincidence of wants] required in other systems of trade such as barter. Currency adoption and acceptance can be global, national, or in some cases local or community-based.

===Banks===

Alice need not provide currency to Bob in-person. She may instead transfer this value by first entrusting her currency to a bank who promises to store and protect Alice's currency notes. The bank gives Alice a written promise (called a "bank statement") that entitles her to withdraw the same number of currency bills that she deposited. Since the money is still Alice's, she is entitled to do with it whatever she pleases, and the bank (like most banks), for a small fee, will do Alice the service of passing on the currency bills to Bob on her behalf. This is done by Alice's bank by giving the dollar bills to Bob's bank and informing them that the money is for Bob, who will then see the amount the next time he checks his balance or receives his bank statement.

Since banks have many customers, and bank employees require money for doing the job of talking to people and signing documents, banks in recent times have been using machines such as ATMs and web servers that do the job of interacting with customers instead of paid bank employees. The task of these machines is to learn what each customer wants to do with their money and, to the extent that it is possible, act on what the customer wants (for example, ATMs can hand out cash). Customers can always know how much money they have in their accounts, and they are confident that the numbers they see in their bank statements and on their computer screens accurately reflect the number of dollars that they can get from the bank on demand. They can be so sure of this that they can accept those numbers in the same way they accept paper banknotes (this is similar to the way people started accepting paper dollars when they had been accepting gold or silver).

Such a system has several disadvantages:
* It is costly. [https://en.wikipedia.org/wiki/Electronic_funds_transfer EFTs] in Europe can cost 25 euros. Credit transactions can cost several percent of the transaction.
* It is slow. Checking and low cost wire services take days to complete.
* In most cases, it cannot be anonymous.
* Accounts can be frozen, or their balance partially or wholly confiscated.
* Banks and other payment processors like PayPal, Visa, and Mastercard may refuse to process payments for certain legal entities.

Bitcoin is a system of owning and voluntarily transferring amounts of so-called ''bitcoins'', in a manner similar to an on-line banking, but pseudonymously and without reliance on a central authority to maintain account balances. If bitcoins are valuable, it is because they are useful and limited in supply.

==Bitcoin Basics==

===Creation of coins===

New coins are slowly [[Mining|mined]] into existence by following a mutually agreed-upon set of rules. A user [[Mining|mining]] bitcoins is running a software program that searches tirelessly for a solution to a very difficult math problem whose difficulty is precisely known. The difficulty is automatically adjusted regularly so that the number of solutions found globally, by everyone, for a given unit of time is constant: an average of 6 per hour. When a solution is found, the user may tell everyone of the existence of this newly found solution, along with other information, packaged together in what is called a "[[Block|block]]".

Blocks create 25 new bitcoins at present. This amount, known as the block reward, is an incentive for people to perform the computation work required for generating blocks. Roughly every 4 years, the number of bitcoins that can be "mined" in a block reduces by 50%. Originally the block reward was 50 bitcoins; it halved in November 2012. Any block that is created by a malicious user that does not follow this rule (or any other rules) will be rejected by everyone else. In the end, no more than 21 million bitcoins will ever exist.

Because the block reward will decrease over the long term, miners will some day instead pay for their hardware and electricity costs by collecting [[Transaction_fee|transaction fees]]. The sender of money may voluntarily pay a small transaction fee which will be kept by whoever finds the next block. Paying this fee will encourage miners to include the transaction in a block more quickly.

===Sending payments===

To guarantee that a third-party, let's call her Eve, cannot spend other people's bitcoins by creating transactions in their names, Bitcoin uses [[Wikipedia:Public-key_cryptography|public key cryptography]] to make and verify digital signatures. In this system, each person, such as Alice or Bob, has one or more addresses each with an associated pair of public and private keys that they may hold in a [[Wallet|wallet]]. Only the user with the private key can sign a transaction to give some of their bitcoins to somebody else, but anyone can validate the signature using that user’s public key.

Suppose Alice wants to send a bitcoin to Bob.
* Bob sends his address to Alice.
* Alice adds Bob’s address and the amount of bitcoins to transfer to a message: a 'transaction' message.
* Alice signs the transaction with her private key, and announces her public key for signature verification.
* Alice broadcasts the transaction on the Bitcoin network for all to see.

(Only the first two steps require human action. The rest is done by the Bitcoin client software.)

Looking at this transaction from the outside, anyone who knows that these addresses belong to Alice and Bob can see that Alice has agreed to transfer the amount to Bob, because nobody else has Alice's private key. Alice would be foolish to give her private key to other people, as this would allow them to sign transactions in her name, removing funds from her control.

Later on, when Bob wishes to transfer the same bitcoins to Charley, he will do the same thing:
* Charlie sends Bob his address.
* Bob adds Charlie's address and the amount of bitcoins to transfer to a message: a 'transaction' message.
* Bob signs the transaction with his private key, and announces his public key for signature verification.
* Bob broadcasts the transaction on the Bitcoin network for all to see.

Only Bob can do this because only he has the private key that can create a valid signature for the transaction.

Eve cannot change whose coins these are by replacing Bob’s address with her address, because Alice signed the transfer to Bob using her own private key, which is kept secret from Eve, and instructing that the coins which were hers now belong to Bob. So if Charlie accepts that the original coin was in the hands of Alice, he will also accept the fact that this coin was later passed to Bob, and now Bob is passing this same coin to him.

===Preventing [[double-spending]]===

The process described above does not prevent Alice from using the same bitcoins in more than one transaction. The following process does; this is the primary innovation behind Bitcoin.

* Details about the [[Transactions|transaction]] are [[Network|sent and forwarded]] to all or as many other computers as possible.
* A constantly growing chain of [[Blocks|blocks]] that contains a record of all transactions is collectively maintained by all computers (each has a full copy).
* To be accepted in the chain, transaction blocks must be valid and must include [[proof of work]] (one block generated by the network every 10 minutes).
* Blocks are chained in a way so that, if any one is modified, all following blocks will have to be recomputed.
* When multiple valid continuations to this chain appear, only the longest such branch is accepted and it is then extended further.

When Bob sees that his transaction has been included in a block, which has been made part of the single longest and fastest-growing block chain (extended with significant computational effort), he can be confident that the transaction by Alice has been accepted by the computers in the network and is permanently recorded, preventing Alice from creating a second transaction with the same coin. In order for Alice to thwart this system and double-spend her coins, she would need to muster more computing power than all other Bitcoin users combined.

===Anonymity===

When it comes to the Bitcoin network itself, there are no "accounts" to set up, and no e-mail addresses, user-names or passwords are required to hold or spend bitcoins. Each balance is simply associated with an address and its public-private key pair. The money "belongs" to anyone who has the private key and can sign transactions with it. Moreover, those keys do not have to be registered anywhere in advance, as they are only used when required for a transaction. Transacting parties do not need to know each other's identity in the same way that a store owner does not know a cash-paying customer's name.

A [[Address|Bitcoin address]] mathematically corresponds to a public key and looks like this:

:1PHYrmdJ22MKbJevpb3MBNpVckjZHt89hz

Each person can have many such addresses, each with its own balance, which makes it very difficult to know which person owns what amount. In order to protect his [[Anonymity|privacy]], Bob can generate a new public-private key pair for each individual receiving transaction and the Bitcoin software encourages this behavior by default. Continuing the example from above, when Charlie receives the bitcoins from Bob, Charlie will not be able to identify who owned the bitcoins before Bob.

===Capitalization / Nomenclature===

Since Bitcoin is both a currency and a protocol, capitalization can be confusing. Accepted practice is to use ''Bitcoin'' (singular with an upper case letter B) to label the protocol, software, and community, and ''bitcoins'' (with a lower case b) to label units of the currency.

==Where to see and explore==

You can directly explore the system in action by visiting [https://www.biteasy.com/ Biteasy.com], [http://blockchain.info/ Blockchain.info], [http://btc.blockr.io/ Blokr.io Bitcoin Block Explorer] or [http://blockexplorer.com/ Bitcoin Block Explorer].
The site shows you the latest blocks in the block chain. The [[Block_chain|block chain]] contains the agreed history of all transactions that took place in the system.
Note how many blocks were generated in the last hour, which on average will be 6. Also notice the number of transactions and the total amount transferred in the last hour (last time I checked it was about 64 and 15K).
This should give you an indication of how active the system is.

Next, navigate to one of these blocks.
The block's [[hash]] begins with a run of zeros. This is what made creating the block so difficult; a hash that begins with many zeros is much more difficult to find than a hash with few or no zeros. The computer that generated this block had to try many ''Nonce'' values (also listed on the block's page) until it found one that generated this run of zeros.
Next, see the line titled ''Previous block''. Each block contains the hash of the block that came before it. This is what forms the chain of blocks.
Now take a look at all the transactions the block contains. The first transaction is the income earned by the computer that generated this block. It includes a fixed amount of coins created out of "thin air" and possibly a fee collected from other transactions in the same block.

Drill down into any of the transactions and you will see how it is made up of one or more amounts coming in and out.
Having more than one incoming and outgoing amount in a transaction enables the system to join and break amounts in any possible way, allowing for any fractional amount needed. Each incoming amount is a past transaction (which you can also view) from someone's address, and each outgoing amount is addressed to someone and will be part of a future transaction (which you can also navigate down into if it has already taken place.)

Finally you can follow any of the [[Address|addresses]] links and see what public information is available for them.

To get an impression of the amount of activity on the Bitcoin network, you might like to visit the monitoring websites [[Bitcoin Monitor]] and [[Bitcoin Watch]]. The first shows a real-time visualization of events on the Bitcoin network, and the second lists general statistics on the amount and size of recent transactions.

===How many people use Bitcoin?===

This is quite a difficult question to answer accurately. One approach is to count how many bitcoin clients connected to the network in the last 24 hours. We can do this because some clients transmit their addresses to the other members of the network periodically. In September 2011 this method suggested that there were about {{formatnum:60000}} users.

==See Also==
* Get started buying bitcoins at [http://coinbase.com/?r=514b6eb6a18f2fdde50000db&utm_campaign=user-referral&src=referral-link Coinbase].
* [http://bitcoinhelp.net Bitcoin Help] — the simple guide to Bitcoin.
* Learn the entire history of Bitcoin in the interactive timeline at [http://historyofbitcoin.org History of Bitcoin].
* [http://bitcoinX.io BitcoinX.io] Website Dedicated to Providing Users with the Best Information on Where to Buy, Sell and Trade Bitcoins. Covers all of the Major Exchanges.
* [[File:MCS_200by200_logo-01.png|20px|link=http://www.mycoinsolution.com]][http://www.mycoinsolution.com My Coin Solution] - For business that want to learn more about Bitcoin
* [https://www.trybtc.com/ TryBTC] easiest way to get started using bitcoin. Gives you free coins to create a bitcoin wallet and start spending.
* [http://www.youtube.com/watch?v=Um63OQz3bjo What is Bitcoin?] video introduction
* Installing Bitcoin [[getting started]]
* [[Using Bitcoin]]
* A gentle introduction to Bitcoin - [[BitcoinMe]]
* [http://coinlab.com/2011/12/bitcoin-primer Bitcoin Primer] from CoinLab
* Another introduction, ''The Rebooting Of Money'' podcast is found at [[Bitcoin Money]]
* A beginner's step-by-step guide to using Bitcoin, use of alternative wallets, and generally keeping your money and computer secure - [http://BitcoinIntro.com BitcoinIntro.com]
* [http://howtobitcoin.info howtobitcoin.info] Directory of bitcoin links for beginners
* Amazon Kindle Book [http://www.amazon.com/Bitcoin-Step-by-ebook/dp/B00A1CUQQU Bitcoin Step by Step] $3.99 (USD). The author walks you step by step through getting started.
* [http://dpassport.com/free-reports/Free-Bitcoin-Report.pdf Free Bitcoin report] by Brad Gosse and Jennifer Wozniak

[[zh-cn:简介]]

[[de:Einführung]]
[[fr:Introduction]]

Help:Introduction

2014-08-15T02:15:14Z

DoctorBTC:

The purpose of this page is to provide a general overview of the Bitcoin system and economy.

==Basic Concepts==

===Currency===

Alice wants to buy the [http://www.grasshillalpacas.com/alpacaproductsforbitcoinoffer.html Alpaca socks] which Bob has for sale. In return, she must provide something of equal value to Bob. The most efficient way to do this is by using a medium of exchange that Bob accepts which would be classified as currency. Currency makes trade easier by eliminating the need for [http://en.wikipedia.org/wiki/Coincidence_of_wants coincidence of wants] required in other systems of trade such as barter. Currency adoption and acceptance can be global, national, or in some cases local or community-based.

===Banks===

Alice need not provide currency to Bob in-person. She may instead transfer this value by first entrusting her currency to a bank who promises to store and protect Alice's currency notes. The bank gives Alice a written promise (called a "bank statement") that entitles her to withdraw the same number of currency bills that she deposited. Since the money is still Alice's, she is entitled to do with it whatever she pleases, and the bank (like most banks), for a small fee, will do Alice the service of passing on the currency bills to Bob on her behalf. This is done by Alice's bank by giving the dollar bills to Bob's bank and informing them that the money is for Bob, who will then see the amount the next time he checks his balance or receives his bank statement.

Since banks have many customers, and bank employees require money for doing the job of talking to people and signing documents, banks in recent times have been using machines such as ATMs and web servers that do the job of interacting with customers instead of paid bank employees. The task of these machines is to learn what each customer wants to do with their money and, to the extent that it is possible, act on what the customer wants (for example, ATMs can hand out cash). Customers can always know how much money they have in their accounts, and they are confident that the numbers they see in their bank statements and on their computer screens accurately reflect the number of dollars that they can get from the bank on demand. They can be so sure of this that they can accept those numbers in the same way they accept paper banknotes (this is similar to the way people started accepting paper dollars when they had been accepting gold or silver).

Such a system has several disadvantages:
* It is costly. [https://en.wikipedia.org/wiki/Electronic_funds_transfer EFTs] in Europe can cost 25 euros. Credit transactions can cost several percent of the transaction.
* It is slow. Checking and low cost wire services take days to complete.
* In most cases, it cannot be anonymous.
* Accounts can be frozen, or their balance partially or wholly confiscated.
* Banks and other payment processors like PayPal, Visa, and Mastercard may refuse to process payments for certain legal entities.

Bitcoin is a system of owning and voluntarily transferring amounts of so-called ''bitcoins'', in a manner similar to an on-line banking, but pseudonymously and without reliance on a central authority to maintain account balances. If bitcoins are valuable, it is because they are useful and limited in supply.

==Bitcoin Basics==

===Creation of coins===

The creation of coins must be limited for the currency to have any value.

New coins are slowly [[Mining|mined]] into existence by following a mutually agreed-upon set of rules. A user [[Mining|mining]] bitcoins is running a software program that searches tirelessly for a solution to a very difficult math problem whose difficulty is precisely known. The difficulty is automatically adjusted regularly so that the number of solutions found globally, by everyone, for a given unit of time is constant: an average of 6 per hour. When a solution is found, the user may tell everyone of the existence of this newly found solution, along with other information, packaged together in what is called a "[[Block|block]]".

Blocks create 25 new bitcoins at present. This amount, known as the block reward, is an incentive for people to perform the computation work required for generating blocks. Roughly every 4 years, the number of bitcoins that can be "mined" in a block reduces by 50%. Originally the block reward was 50 bitcoins; it halved in November 2012. Any block that is created by a malicious user that does not follow this rule (or any other rules) will be rejected by everyone else. In the end, no more than 21 million bitcoins will ever exist.

Because the block reward will decrease over the long term, miners will some day instead pay for their hardware and electricity costs by collecting [[Transaction_fee|transaction fees]]. The sender of money may voluntarily pay a small transaction fee which will be kept by whoever finds the next block. Paying this fee will encourage miners to include the transaction in a block more quickly.

===Sending payments===

To guarantee that a third-party, let's call her Eve, cannot spend other people's bitcoins by creating transactions in their names, Bitcoin uses [[Wikipedia:Public-key_cryptography|public key cryptography]] to make and verify digital signatures. In this system, each person, such as Alice or Bob, has one or more addresses each with an associated pair of public and private keys that they may hold in a [[Wallet|wallet]]. Only the user with the private key can sign a transaction to give some of their bitcoins to somebody else, but anyone can validate the signature using that user’s public key.

Suppose Alice wants to send a bitcoin to Bob.
* Bob sends his address to Alice.
* Alice adds Bob’s address and the amount of bitcoins to transfer to a message: a 'transaction' message.
* Alice signs the transaction with her private key, and announces her public key for signature verification.
* Alice broadcasts the transaction on the Bitcoin network for all to see.

(Only the first two steps require human action. The rest is done by the Bitcoin client software.)

Looking at this transaction from the outside, anyone who knows that these addresses belong to Alice and Bob can see that Alice has agreed to transfer the amount to Bob, because nobody else has Alice's private key. Alice would be foolish to give her private key to other people, as this would allow them to sign transactions in her name, removing funds from her control.

Later on, when Bob wishes to transfer the same bitcoins to Charley, he will do the same thing:
* Charlie sends Bob his address.
* Bob adds Charlie's address and the amount of bitcoins to transfer to a message: a 'transaction' message.
* Bob signs the transaction with his private key, and announces his public key for signature verification.
* Bob broadcasts the transaction on the Bitcoin network for all to see.

Only Bob can do this because only he has the private key that can create a valid signature for the transaction.

Eve cannot change whose coins these are by replacing Bob’s address with her address, because Alice signed the transfer to Bob using her own private key, which is kept secret from Eve, and instructing that the coins which were hers now belong to Bob. So if Charlie accepts that the original coin was in the hands of Alice, he will also accept the fact that this coin was later passed to Bob, and now Bob is passing this same coin to him.

===Preventing [[double-spending]]===

The process described above does not prevent Alice from using the same bitcoins in more than one transaction. The following process does; this is the primary innovation behind Bitcoin.

* Details about the [[Transactions|transaction]] are [[Network|sent and forwarded]] to all or as many other computers as possible.
* A constantly growing chain of [[Blocks|blocks]] that contains a record of all transactions is collectively maintained by all computers (each has a full copy).
* To be accepted in the chain, transaction blocks must be valid and must include [[proof of work]] (one block generated by the network every 10 minutes).
* Blocks are chained in a way so that, if any one is modified, all following blocks will have to be recomputed.
* When multiple valid continuations to this chain appear, only the longest such branch is accepted and it is then extended further.

When Bob sees that his transaction has been included in a block, which has been made part of the single longest and fastest-growing block chain (extended with significant computational effort), he can be confident that the transaction by Alice has been accepted by the computers in the network and is permanently recorded, preventing Alice from creating a second transaction with the same coin. In order for Alice to thwart this system and double-spend her coins, she would need to muster more computing power than all other Bitcoin users combined.

===Anonymity===

When it comes to the Bitcoin network itself, there are no "accounts" to set up, and no e-mail addresses, user-names or passwords are required to hold or spend bitcoins. Each balance is simply associated with an address and its public-private key pair. The money "belongs" to anyone who has the private key and can sign transactions with it. Moreover, those keys do not have to be registered anywhere in advance, as they are only used when required for a transaction. Transacting parties do not need to know each other's identity in the same way that a store owner does not know a cash-paying customer's name.

A [[Address|Bitcoin address]] mathematically corresponds to a public key and looks like this:

:1PHYrmdJ22MKbJevpb3MBNpVckjZHt89hz

Each person can have many such addresses, each with its own balance, which makes it very difficult to know which person owns what amount. In order to protect his [[Anonymity|privacy]], Bob can generate a new public-private key pair for each individual receiving transaction and the Bitcoin software encourages this behavior by default. Continuing the example from above, when Charlie receives the bitcoins from Bob, Charlie will not be able to identify who owned the bitcoins before Bob.

===Capitalization / Nomenclature===

Since Bitcoin is both a currency and a protocol, capitalization can be confusing. Accepted practice is to use ''Bitcoin'' (singular with an upper case letter B) to label the protocol, software, and community, and ''bitcoins'' (with a lower case b) to label units of the currency.

==Where to see and explore==

You can directly explore the system in action by visiting [https://www.biteasy.com/ Biteasy.com], [http://blockchain.info/ Blockchain.info], [http://btc.blockr.io/ Blokr.io Bitcoin Block Explorer] or [http://blockexplorer.com/ Bitcoin Block Explorer].
The site shows you the latest blocks in the block chain. The [[Block_chain|block chain]] contains the agreed history of all transactions that took place in the system.
Note how many blocks were generated in the last hour, which on average will be 6. Also notice the number of transactions and the total amount transferred in the last hour (last time I checked it was about 64 and 15K).
This should give you an indication of how active the system is.

Next, navigate to one of these blocks.
The block's [[hash]] begins with a run of zeros. This is what made creating the block so difficult; a hash that begins with many zeros is much more difficult to find than a hash with few or no zeros. The computer that generated this block had to try many ''Nonce'' values (also listed on the block's page) until it found one that generated this run of zeros.
Next, see the line titled ''Previous block''. Each block contains the hash of the block that came before it. This is what forms the chain of blocks.
Now take a look at all the transactions the block contains. The first transaction is the income earned by the computer that generated this block. It includes a fixed amount of coins created out of "thin air" and possibly a fee collected from other transactions in the same block.

Drill down into any of the transactions and you will see how it is made up of one or more amounts coming in and out.
Having more than one incoming and outgoing amount in a transaction enables the system to join and break amounts in any possible way, allowing for any fractional amount needed. Each incoming amount is a past transaction (which you can also view) from someone's address, and each outgoing amount is addressed to someone and will be part of a future transaction (which you can also navigate down into if it has already taken place.)

Finally you can follow any of the [[Address|addresses]] links and see what public information is available for them.

To get an impression of the amount of activity on the Bitcoin network, you might like to visit the monitoring websites [[Bitcoin Monitor]] and [[Bitcoin Watch]]. The first shows a real-time visualization of events on the Bitcoin network, and the second lists general statistics on the amount and size of recent transactions.

===How many people use Bitcoin?===

This is quite a difficult question to answer accurately. One approach is to count how many bitcoin clients connected to the network in the last 24 hours. We can do this because some clients transmit their addresses to the other members of the network periodically. In September 2011 this method suggested that there were about {{formatnum:60000}} users.

==See Also==
* Get started buying bitcoins at [http://coinbase.com/?r=514b6eb6a18f2fdde50000db&utm_campaign=user-referral&src=referral-link Coinbase].
* [http://bitcoinhelp.net Bitcoin Help] — the simple guide to Bitcoin.
* Learn the entire history of Bitcoin in the interactive timeline at [http://historyofbitcoin.org History of Bitcoin].
* [http://bitcoinX.io BitcoinX.io] Website Dedicated to Providing Users with the Best Information on Where to Buy, Sell and Trade Bitcoins. Covers all of the Major Exchanges.
* [[File:MCS_200by200_logo-01.png|20px|link=http://www.mycoinsolution.com]][http://www.mycoinsolution.com My Coin Solution] - For business that want to learn more about Bitcoin
* [https://www.trybtc.com/ TryBTC] easiest way to get started using bitcoin. Gives you free coins to create a bitcoin wallet and start spending.
* [http://www.youtube.com/watch?v=Um63OQz3bjo What is Bitcoin?] video introduction
* Installing Bitcoin [[getting started]]
* [[Using Bitcoin]]
* A gentle introduction to Bitcoin - [[BitcoinMe]]
* [http://coinlab.com/2011/12/bitcoin-primer Bitcoin Primer] from CoinLab
* Another introduction, ''The Rebooting Of Money'' podcast is found at [[Bitcoin Money]]
* A beginner's step-by-step guide to using Bitcoin, use of alternative wallets, and generally keeping your money and computer secure - [http://BitcoinIntro.com BitcoinIntro.com]
* [http://howtobitcoin.info howtobitcoin.info] Directory of bitcoin links for beginners
* Amazon Kindle Book [http://www.amazon.com/Bitcoin-Step-by-ebook/dp/B00A1CUQQU Bitcoin Step by Step] $3.99 (USD). The author walks you step by step through getting started.
* [http://dpassport.com/free-reports/Free-Bitcoin-Report.pdf Free Bitcoin report] by Brad Gosse and Jennifer Wozniak

[[zh-cn:简介]]

[[de:Einführung]]
[[fr:Introduction]]

Buying bitcoins

2014-06-26T00:40:36Z

DoctorBTC:

There are various methods available for '''buying bitcoins'''. If you are located in the USA, [http://coinbase.com/?r=514b6eb6a18f2fdde50000db&utm_campaign=user-referral&src=referral-link Coinbase] is your best option. See [[Buying Bitcoins (the noob version)|here for a Newb-friendly version]] of this page.

'''NOTE:''' For taking advantage of Bitcoin volatility you are able to trade CFDs through [http://www.avatrade.com/lp/trade-bitcoin?tag=39206&tag2 AvaTrade] or [http://www.plus500.com/Instruments/BTCUSD?id=73407&pl=2 Plus500]. When trading online your capital may be at risk. Trading CFDs is suitable for more experienced traders.

{{Counterparty-warning}}

==Market Exchanges==

Market exchanges are those in which buy orders are matched with sell orders, so the price offered depends on the market. If a service quotes a price then it is not operating a [http://bitcoincharts.com/markets market] but instead is a broker that buys and/or sells coins. Those exchanges are found in the list of [[Buying bitcoins#Fixed_Rate_Exchanges_.26_Others|fixed-rate exchanges]].

Exchanges are listed in alphabetical order.

{| class="wikitable"
|-
| Exchange || Adding Funds || Withdrawing Funds || Notes
|-
| [[File:Minilogo.png|35px|link=https://www.1bse.com]] [https://1bse.com 1Bse] ([[1Bse|info]])|| BTC LTC DOGE HKD (International Bank Wire) HKD (Local Bank Transfer) USD (International Bank Wire) USD (Payeer.com including Yandex.money, Perfect Money, QIWI) USD (Local Bank Transfer) EUR (International Bank Wire) EUR (Local Bank Transfer) EUR (Payeer.com including Yandex.money, Perfect Money, QIWI) SGD (International Bank Wire) SGD (Local Bank Transfer) CNY (Local Bank Transfer) CNY (International Bank Wire) || BTC LTC DOGE HKD (International Bank Wire) HKD (Local Bank Transfer) USD (International Bank Wire) USD (Payeer.com including Yandex.money, Perfect Money, QIWI) USD (Local Bank Transfer) EUR (International Bank Wire) EUR (Local Bank Transfer) EUR (Payeer.com including Yandex.money, Perfect Money, QIWI) SGD (International Bank Wire) SGD (Local Bank Transfer) CNY (Local Bank Transfer) CNY (International Bank Wire) ||<ul><li>Two-Factor Authentication</li><li>Protection from session steal</li><li>24/7 trading monitoring</li><li>No Fees for transfer funds between 1Bse users</li><li>Fees for transaction - 0.15%</li><li>Based in Hong Kong</li><li>Language: English</li></ul>
|-
| [[File:ANXIcon.png|20px|link=https://anxbtc.com]] [https://anxbtc.com ANXBTC]([https://en.bitcoin.it/wiki/Asia_Nexgen_Bitcoin_Exchange info)] || BTC HKD (International Bank Wire) HKD (Local Bank Transfer) HKD (In Store Cash Deposit) USD (International Bank Wire) USD (EgoPay) AUD (Local Bank Transfer) AUD (International Bank Wire) CAD (International Bank Wire) CHF (International Bank Wire) EUR (SEPA) EUR (International Bank Wire) EUR (EgoPay) GBP (International Bank Wire) JPY (International Bank Wire) NZD (International Bank Wire) SGD (International Bank Wire) || BTC HKD (International Bank Wire) HKD (Local Bank Transfer) USD (International Bank Wire) USD (EgoPay) AUD (Local Bank Transfer) AUD (International Bank Wire) CAD (International Bank Wire) CHF (International Bank Wire) EUR (SEPA) EUR (International Bank Wire) EUR (EgoPay) GBP (International Bank Wire) JPY (International Bank Wire) NZD (International Bank Wire) SGD (International Bank Wire) || <ul> <li>Trading Fees as low as 0.05%</li><li>Zero Bank Transfer Deposit Fees</li><li> Daily processing of withdrawals and deposits Mon-Fri<li>All 10 fiat currency orders are maintained within a single order book</li><li> Registered and based in Hong Kong</li><li> An approved Money Services Operator (MSO) with a license issued by the Hong Kong Customs and Excise Department</li><li>Gox compatible trading API Available</li><li> Multilingual support (English, Traditional Chinese, Simplified Chinese)<li>Two-Factor Authentication</li><li>Accepts cash deposits at the world's first Bitcoin retail store</li><li>Native wallet apps for both [https://play.google.com/store/apps/details?id=com.anxbtc.android Android] and [https://itunes.apple.com/us/app/anx-vault-your-bitcoin-wallet/id855057847?ls=1&mt=8 iOS]</li></ul>
|-
| [[File:ANXIcon.png|20px|link=https://anxpro.com]] [https://anxpro.com ANXPRO]([https://en.bitcoin.it/wiki/Asia_Nexgen_Bitcoin_Exchange info)] || BTC LTC PPC NMC DOGE HKD (International Bank Wire) HKD (Local Bank Transfer) HKD (In Store Cash Deposit) USD (International Bank Wire) USD (EgoPay) AUD (Local Bank Transfer) AUD (International Bank Wire) CAD (International Bank Wire) CHF (International Bank Wire) EUR (SEPA) EUR (International Bank Wire) EUR (EgoPay) GBP (International Bank Wire) JPY (International Bank Wire) NZD (International Bank Wire) SGD (International Bank Wire) || BTC LTC PPC NMC DOGE HKD (International Bank Wire) HKD (Local Bank Transfer) USD (International Bank Wire) USD (EgoPay) AUD (Local Bank Transfer) AUD (International Bank Wire) CAD (International Bank Wire) CHF (International Bank Wire) EUR (SEPA) EUR (International Bank Wire) EUR (EgoPay) GBP (International Bank Wire) JPY (International Bank Wire) NZD (International Bank Wire) SGD (International Bank Wire) || <ul> <li>Trading Fees as low as 0.05%</li><li>Zero Bank Transfer Deposit Fees</li><li>The only crypto-currency exchange in the world that facilitates Altcoin trading in ALL major currencies</li><li> Daily processing of withdrawals and deposits Mon-Fri<li>All 10 fiat currency orders are maintained within a single order book</li><li> Registered and based in Hong Kong</li><li> An approved Money Services Operator (MSO) with a license issued by the Hong Kong Customs and Excise Department</li><li>Gox compatible trading API Available, inc. support for Altcoins</li><li> Multilingual support (English, Traditional Chinese, Simplified Chinese)<li>Two-Factor Authentication</li><li>Accepts cash deposits at the world's first Bitcoin retail store</li><li>Advanced trading interface including support for keyboard hotkeys (i.e. 'B' for Buy, 'L' for Limit, 'Enter' to execute, etc)</li><li>Native wallet apps for both [https://play.google.com/store/apps/details?id=com.anxbtc.android Android] and [https://itunes.apple.com/us/app/anx-vault-your-bitcoin-wallet/id855057847?ls=1&mt=8 iOS]</li></ul>
|-
| [[File:BitQuickco.png|20px|link=https://www.bitquick.co]] [https://www.bitquick.co BitQuick.co]([https://en.bitcoin.it/wiki/BitQuick.co info)] || BTC Cash Deposit SEPA Transfer (International) || BTC|| Connects buyers to sellers around the globe via bank cash deposit or SEPA transfer. No registration required. Instant deposit to any bitcoin address after cash deposit or SEPA transfer receipt received.
|-
| [https://www.bitsource.org BitSource.org]([https://en.bitcoin.it/wiki/BitSource info)] || BTC LTC PPC Visa Mastercard Cash Deposit SEPA Transfer (International) OKPay Payeer EgoPay SWIFT Transfers/Bank wire PerfectMoney MoneyPak || BTC LTC PPC Bank Wire|| BitSource.org is a crypto-currency exchange platform focused on simplifying the purchase and sale of Bitcoin, Litecoin, and other crypto-currencies. The company holds up to 98% of customer funds in cold wallets and offline in bank vaults to prevent theft or loss.
|-
| [[Bitcoin Central]] || BTC EUR (SEPA bank transfer) International wire transfer || BTC EUR (SEPA bank transfer) International wire transfer ||
|-
| [[bitNZ]] || BTC NZD (Cash depost as Westbank) || BTC NZD (Domestic bank transfer) ||
|-
| [https://www.bitfinex.com/ Bitfinex] || BTC USD (Intl wire)|| BTC USD (Intl wire) ||
|-
| [[Bitstamp]] || BTC EUR (SEPA transfer) USD (Intl wire) USD ([[Ripple]]) CHF || BTC BTC (Redeemable code) EUR (SEPA transfer) USD (Intl wire) USD (Ripple) CHF || EUR and CHF deposits converted to/from USD for trading
|-
| [https://bitcoin-24.com Bitcoin-24] || BTC EUR (SEPA transfer) EUR (Credit Card) EUR (SOFORT Überweisung || BTC EUR (SEPA transfer) || SOFORT Überweisung and Credit Card deposits are instant
|-
| [https://BTCMarkets.net BTCMarkets.net] || BTC LTC AUD (Local Bank Transfer) AUD (Westpac Branch Cash Deposit) || BTC LTC AUD (Local Bank Transfer) || <ul><li>Australia's only locally based full service Bitcoin and Litecoin exchange.</li><li>Branch cash deposits (1-3 hours to clear)</li><li>Fast domestic bank transfers (1-2 business days to clear)</li><li>No deposit or withdrawal fees</li><li>No international bank or currency conversion fees</li><li>Australian owned and operated company with local support</li><li>Trading fees from as low as 0.6%.</li><li>[https://BTCMarkets.net BTCMarkets.net]</li></ul>
|-
| [http://BTCTurk.com BTCTurk.com] || BTC TL (Bank transfer) || BTC TL (Bank transfer) || <ul><li> The first Bitcoin exchange to allow trades in Turkish Lira.</li><li> Available in Turkish language. </li></ul>
|-
| [[BTC-E]] || BTC BTC (BTC-e redeemable code) USD (Cash deposit at Post of Russia) USD (Cash deposit at banks including Privatbank, Savings Bank of Russia (Sberbank), RU/UA Terminals, & more) USD (Interkassa) USD (WebMoney - WMZ) USD (Yandex) USD (LiqPay) USD (Perfect Money) USD (QIWI) USD (OKPay) USD (RBK Money) USD (Ditial currencies including НСМЭП (NSMEP), Единый Кошелек (Unified Purse), TeleMoney, & more) USD (International bank wire) EUR (SEPA bank transfer) RUB (QIWI) RUB (LiqPay) RUB (WebMoney-WMR) RUB (BTC-e Redeemable code) RUB (Bank transfer) || BTC BTC (BTC-e redeemble code) USD (Webmoney - WMZ) USD (Perfect Money) USD (LiqPay) USD (QIWI) USD (PayPal) USD (OKPay) USD (Payza/AlertPay) USD (Privat, Privat UAH) USD (Cash deposit into Savings Bank/Sberbank, Telebank, Alfa Bank) USD (BTC-e Redeemable Code) USD (International Wire Transfer) EUR (SEPA bank transfer) RUB (Cash delivery, possible in Moscow) RUB (QIWI) RUB (LiqPay) RUB (WebMoney WMR) RUB (Яндекс.Деньги Yandex) RUB (RBK Money) Cash deposit (into account at Сбербанка России!/Savings Bank/Sberbank, Телебанк (Telebank), and АльфаБанк (Alfa Bank) RUB (Transfer to credit card VISA & MasterCard) RUB (BTC-e Redeemable code) RUB (Bank transfer) || Language: English, Russian. Interkassa can be funded from Webmoney and many other methods. BitInstant Can be funding option includes QIWI, Cyberplat.
|-
| [https://CampBX.com/ CampBX] (CBX) || BTC USD ([[Dwolla]]) USD (P2P bank transfer at Chase, B of A, Wells Fargo and ING. Credited after three business days). USD (Personal Check) USD (USPS Postal money order, Canada Post money order) || BTC USD ([[Dwolla]]) USD (ACH Direct Deposit) USD (USPS Postal Money Order) USD (Domestic bank wire) USD (International bank wire) || <ul> <li> Security certification from McAfee</li><li> Advanced trading options with AON/FOK/Market</li> <li>STOPLOSS and Short-Selling in Pipeline</li><li> Trading API available</li><li> Wallet API available </li><li> CBX Instant Bitcoin Transfers Feature </li><li> Stoploss / Custom Order Expiry Date/Time </li><li> SMS (Text Message) Notifications </li> <li> Two-Factor Authentication </li> <li> Based in USA - Atlanta </li> </ul>
|-
| [[CoinMKT]] || | BTC | LTC | PPC | TRC | NVC | NMC | FTC USD ([[Dwolla]]) USD (P2P bank transfer at any US bank, credited after three business days). USD (Personal Check) USD (USPS Postal money order, Canada Post money order) || | BTC | LTC | PPC | TRC | NVC | NMC | FTC USD ([[Dwolla]]) USD (USPS Postal Money Order) USD (Domestic bank wire) USD (International bank wire) || <ul> <li>Trade any currency pair</li><li>Fast, web-based ID verification</li><li>Focused on user experience</li><li>Play money trading</li> <li> Based in Santa Monica, CA </li> </ul>
|-
| [[File:e-cointrade.com logo.png|link=https://www.e-cointrade.com/cointrade/content.jsp?language=English&ref=en.bitcoin.it&id=Home]] [https://www.e-cointrade.com/cointrade/content.jsp?language=English&ref=en.bitcoin.it&id=Home e-CoinTrade.com] ([[e-cointrade.com|info]]) || | Deposits: BTC | LTC | FTC | IXC | NVC | MNC | TRC | PPC USD ([[Perfect Money]]) EUR ([[Perfect Money]]) || | Withdrawals: BTC | LTC | FTC | IXC | NVC | MNC | TRC | PPC USD ([[Perfect Money]]) EUR ([[Perfect Money]]) || <ul><li> Focused in '''symplicity''' for the average user.</li><li> Full multilanguage, available in: English, Deutche, Español, Pусский, Français. </li> <li> Automatic trading platform.</li><li> Trade in any combination of the currency pairs.</li><li> Live ''chatbox'' for users.</li></ul>
|-
| [[FYB-SG]] || BTC SGD(Internet Bank Transfer) SGD (Annonymous Cash Deposit at any UOB Cash Deposit Machine in Singapore). || BTC SGD(Internet Bank Transfer) || Based in Singapore
|-
| [[FYB-SE]] || BTC SEK(Internet Bank Transfer) || BTC SEK(Internet Bank Transfer) || Based in Sweden
|-
| [[File:Hit_20.png|20px|link=https://www.hitbtc.com]][[HITBTC]] || | BTC LTC EUR (Wire Transfer) USD (Wire Transfer) || | BTC LTC EUR (Wire Transfer) USD (Wire Transfer) || <ul> <li>Cutting-edge technology places and matches order in milliseconds</li><li>Two-factor Authentication</li><li>WebSocket subscription for prices and trades</li><li>Asynchronous WebSocket-based trading interface</li><li>FOK and IOC orders</li><li>API</li>
|-
| [https://www.itbit.com itBit] || BTC SGD(Bank Wire/GIRO) USD (Bank Wire) EUR(Bank Wire)|| BTC SGD(Bank Wire/GIRO) USD (Bank Wire) EUR(Bank Wire) || Based in Singapore
|-
| [http://ice3x.co.za iceCUBED] || BTC LTC ZAR (Local and International Bank Transfer) || BTC LTC ZAR (Local and International Bank Transfer) || <ul><li>South Africa's only locally based full-service Bitcoin and Litecoin exchange</li><li>Fast domestic bank transfers (1-2 business days to clear)</li><li>No deposit or withdrawal fees</li><li>No international bank or currency conversion fees</li><li>South African owned and operated company with local support</li><li>Trading fees from as low as 0.6%.</li><li>[http://ice3x.co.za iceCUBED]</li></ul>
|-
| [[Justcoin]] || | BTC | XRP | LTC NOK (Domestic transfer) EUR (SEPA/International wire transfer) USD (SEPA/International wire transfer) || | BTC | XRP | LTC NOK (Domestic transfer) EUR (SEPA/International wire transfer) USD (SEPA/International wire transfer) || <ul> <li>Based in Oslo, Norway</li><li>Two-factor Authentication</li><li>API</li>
|-
| [[Kapiton.se]] || BTC SEK (Bankgiro Bank Transfer) || BTC SEK (Bankgiro Bank Transfer) ||
|-
| [[Kraken]] || | BTC | XRP | LTC | XVN EUR (SEPA transfer) EUR (International bank wire) USD (Domestic bank wire) USD (International bank wire) || | BTC | XRP | LTC | XVN EUR (SEPA transfer) EUR (International bank wire) USD (Domestic bank wire) USD (International bank wire) USD (ACH) || <ul> <li>Legally compliant</li><li>Advanced Stop Orders</li><li>Margin Trading</li><li>Based in San Francisco, CA</li><li>Two-factor Authentication</li><li>API</li>
|-
| [[File:MMB.png|20px|link=https://www.mengmengbi.cn]] [https://www.mengmengbi.cn Mengmengbi (萌萌币)]([https://en.bitcoin.it/wiki/Mengmengbi info)] || BTC LTC PPC NMC DOGE CNY(Local Bank Transfer) || BTC LTC PPC NMC DOGE CNY(Local Bank Transfer) || <ul> <li>Powered by [https://www.anxpro.com ANX] </li><li>Zero Trading Fees</li><li> Instant processing of CNY deposits</li><li> Near realtime processing of CNY withdraways (Mon-Fri)</li><li>Gox compatible Trading API with BTC, DOGE, LTC, PPC, NMC support</li><li>Zero bank transfer fees</li><li>Shared liquidity with ANX, one of the top 10 Bitcoin exchanges in the world</li><li> Multilingual support (English, Traditional Chinese, Simplified Chinese)<li>Two-Factor Authentication</li></ul>
|-
| [[Rock Currency Exchange]] || BTC EUR (SEPA transfer) SLL (Second Life) USD (Dwolla) || BTC EUR (SEPA transfer) SLL (Second Life) USD (Dwolla) ||
|-
| [[VirtEx]] || BTC CAD (cash deposit at Bank of Montreal or ScotiaBank) CAD (Online bill payment) CAD (Wire transfer) || BTC CAD (direct deposit) CAD (Canada Xpress Post Bank Draft send by mail) CAD Payza (formerly AlertPay) ||
|-
| [https://www.virwox.com/ VirWox] || BTC SLL (Second Life) ACD (Avination) OMC (OpenSim) USD,EUR,GBP,CHF ([[PayPal]]) USD,EUR,GBP (Credit & Debit cards via [[Skrill]]/Moneybookers) USD,EUR,GBP ([http://www.neteller.com NETELLER]) EUR (DIRECTebanking / Sofortuberweisung) USD,EUR,GBP,CHF ([http://www.paysafecard.com PaySafe Card]) EUR (SEPA bank transfer) USD ([[UKash]] vouchers) || BTC SLL (Second Life) ACD (Avination) OMC (OpenSim) USD,EUR,GBP,CHF ([[PayPal]]) USD,EUR,GBP ([[Skrill]]/Moneybookers) USD,EUR,GBP ([http://www.neteller.com NETELLER]) EUR (SEPA bank transfer) || Trading through Second Life Linden Dollars. Variable limits on PayPal and Credit Card deposits.
|-
| [https://www.bitcointoyou.com BitcoinToYou] || BTC BRL USD EUR || BTC BRL USD EUR || Language: Portuguese (português), customer can buy in cash ou bank deposit at HSBC, SANTANDER, ITAÚ, CAIXA, BRADESCO and BANCO DO BRASIL.
|-
| [[MORREX]] || BTC CAD CAD (Online bill payment) CAD (Wire transfer) || BTC CAD CAD (Canada Xpress Post Bank Draft send by mail) CAD ||
|}

==Fixed Rate Exchanges & Others==
For smaller amounts, the options are limited due to bank transfer fees, conversion fees and transaction size restrictions. Options include:

{| class="wikitable"
|-
| Service || Payment Method || Notes
|-
| [https://www.alfacashier.com ALFAcashier] || BTC Bitcoin LTC Litecoin USD PerfectMoney USD LiqPay USD OKPay USD EgoPay USD BTC-E coupon/refill USD (International Bank Wire) EUR (International Bank Wire) RUB (Russian Bank Wire) || Instant exchanger. Language: English, German, Russian, Chinese <ul><li>Cumulative discount system</li><li>Affiliate program</li><li>Fees only 1-3%</li></li>
|-
| [https://www.bestexchangeonline.com Bestexchangeonline.com] || USD PerfectMoney EUR PerfectMoney Cashu Egopay Okpay Bitcoin Webmoney PayPal USD LiqPay RUB || Buy Sell Exchange Bitcoins with the best price. <ul><li>Instant Exchange</li><li>24/7/365 support</li>
|-
| [[File:BitSimpleIcon.png|30px|link=https://BitSimple.com]] [https://BitSimple.com BitSimple.] ([[BitSimple.|info]]) || USD (bank wire) || Don't get goxxed again! We never hold user's bitcoins. Purchased bitcoins will be directly transferred to your personal bitcoin wallet. Stop accepting long delays waiting for funding. We will lock in a rate once you confirm the wire has been sent, and will deliver your purchased coins the same day, usually within an hour.
|-
| [[File:BittyBot-head.png|20px|link=http://BittyBot.co.uk]] [http://BittyBot.co.uk BittyBot] ([[BittyBot|info]]) || GBP (varies person to person) || BittyBot monitors and compares the UK Bitcoin market to help you find the best prices and most reputable traders.
|-
| [https://quickbitcoin.co.uk Quickbitcoin.co.uk] ([[Quickbitcoin|info]]) || GBP (bank transfer) || Buy bitcoins in the UK in under 1 hour from trusted uk seller. Payments by UK bank transfer. No sign up required. [http://www.trustpilot.co.uk/review/quickbitcoin.co.uk See reviews here].
|-
| [https://24change.com 24Change.com] ([[24change.com|info]]) ||
* USD, UAH, RUB, Visa, MasterCard
* C-Coin, eCoin, EgoPay, Payza, Payoneer, EPESE, MoneyGram, OKPAY, WireTransfer, QIWI, Yandex Money, BTC-E code, PayPal, PerfectMoney, Paymer, ePayments, LiqPay, Redpass, WESTERN UNION, C-Gold, Pecunix
* International Banks, Sberbank, Alfa-Bank, Privat24, Svyaznoy Bank, VTB24
||
* Automatic bitcoin and e-currencies buy/sell service
* 24/7/365 fast and reliable e-currencies exchange
* Unlimited reserves
* 15% Affiliate program
|-
|[[File:favicon_b4c.jpg|20px|link=https://bit4coin.net]] [https://bit4coin.net bit4coin.net] ([[bit4coin|info]]) || [https://www.sofort.com SOFORT banking] SEPA transfer (EUR) International bank transfer || Buy bitcoin with gift vouchers: Order bit4coin gift vouchers online at [https://bit4coin.net bit4coin.net] and get them shipped to your door, ready to redeem into bitcoins. No registration required. Perfect for own use or as gift.
|-
| [[File:BitQuickco.png|20px|link=https://www.bitquick.co]] [https://www.bitquick.co BitQuick.co] ([https://en.bitcoin.it/wiki/BitQuick.co info)] || Cash Deposit or SEPA Transfer Only (International) || Connects buyers to sellers around the globe via bank cash deposit or SEPA transfer. No registration required. Instant deposit to any bitcoin address after cash deposit or SEPA transfer receipt received.
|-
| [https://www.cryptxchange.com Cryptxchange] || USD (Cash Deposit) USD (Wire Transfer) CAD (Cash Deposit) CAD (Wire Transfer) You may make cash deposits at any Chase Bank Internationally (ARS, GBP, EUR, AUD, BRL, CLP, COP, EGP, KYD, SAR, CNY, AED, JPY, INR || A multinational US based cryptographic currency exchange. No login or account creation required. No identity verification required. Exquisite customer service. Average transaction time under two hours depending on the time of the day. One of the most anonymous and reliable exchanges on the net. We use SSL & AES-256 military grade encryption for all communication
|-
| [https://www.getbitcoin.com.au Bitcoin (Australia)] || AUD (Bank Deposit) || Bitcoin (Australia) / [https://www.getbitcoin.com.au www.getbitcoin.com.au] offers rapid transfer at low rates.
|-
| [[File:BIPS.gif|20px|link=https://bips.me]] [https://bips.me BIPS] ([[BIPS|info]]) || CAD (Cash deposits in Canada Any Currency (Wire Transfer - Any Country) USD || <ul><li>DK-based</li><li>[https://github.com/BitcoinInternetPaymentSystem BIPS GitHub]</li><li>[https://bips.me/connect/BitcoinInternetPaymentSystemAPI.pdf REST API]</li></ul>
|-
| [http://indo-bitcoin.com Indo-Bitcoin.com] || IDR Mandiri (Cash deposit and wire transfer) IDR BNI (Cash deposit and wire transfer) IDR BCA (Cash deposit and wire transfer) IDR BRI (Cash deposit and wire transfer) || Beli Bitcoin di Indonesia. Lowest fees, max. 30 minutes per transfer, 24 hours 7 days. No verification required.
|-
| [https://Bitcash.cz/market Bitcash.cz] ([[Bitcash.cz|info]]) || CZK domestic wire, EUR with SEPA || Live Auction Rates, person-to-person contract fulfillment
|-
| [https://www.bitbrothersllc.com BitBrothers LLC] || Bank Transfer/Cash/Moneygram || If you are looking for an extremelly simple and anonymous way to purchase bitcoins, this is the best place to do it. We are so sure you will be a repeat customer that we are willing to provide discounts for first time buyers. Best Customer service in the industry.
|-
| [https://truckcoin.com TRUCK COIN] || Bank Transfer/Paypal/Wester Union/Moneygram/Cash/any method with any currency || There is another anonymous way to purchase bitcoins, this is the best safety and anonymous way.
|-
| [https://bitcointalk.org/index.php?topic=237164.0 Bitcoin-Brokers (USA)] || Cash deposit || At major banks like Bank of America, Chase, Wells Fargo, PNC, Citibank. No ID, No registration. Immediate fundings.
|-
| [https://bitcoini.com Bitcoini.com (Bulgaria, Romania)] || BGN (Bank deposit, Cash, EasyPay, Post, Econt) RON (Bank deposit) USD (Western Union, MoneyGram) || Fast and secure way to buy/sell bitcoins. Live support
|-
| [http://www.bitcoinbymobile.com BitcoinByMobile.com] || Mobile Phone (Premium SMS)|| Buy bitcoins instantly using just your mobile phone. No registration or personal financial information needed. Available in: Austria, France, Germany, Luxembourg, Netherlands, Portugal, Spain, and United Kingdom
|-
| [http://www.btc-dealer.com BTC-Dealer] || Credit Card through Liqpay || No signup required. Instant deposit to any bitcoin address
|-
| [https://moneypaktrader.com MoneypakTrader.com] ([[MoneypakTrader.com|info]]) || Moneypak (USD) <======> BTC BTC <======> Moneypak (USD) ReLoadit, etc. (USD) <====> BTC BTC <======> ReLoadit, etc. (USD) || Pays a bonus over market for your BTC Charges a fee over market for your Moneypak, etc. Only accepts codes from original purchaser Attempts to have regular customers processed within 24 hrs Available for discussion via TorChat
|-
| [https://bitbargain.co.uk BitBargain] ([[BitBargain|info]]) || GBP || Quick transactions via Bank Transfer (fast payments support only), Pingit and Ukash. Deals happen between buyer and seller.
|-
| [https://bittylicious.com Bittylicious] ([[Bittylicious|info]]) || GBP, EUR, ZAR || Near instant transactions via UK Bank Transfer (Faster Payments only). No sign up required but can buy more if registered.
|-
| [http://btc.pt BTC.pt] || EUR (Multibanco) || Anonymous transactions. Pay the amount on any Portuguese ATM(MB) or homebanking service, we'll deduce our fee and buy the coins for you at market rate and send them very fast to your wallet. Only available in Portugal.
|-
| [https://www.bitcointrader.com.au Bitcointrader] ([[Bitcointrader|info]]) || AUD (Cash deposit) || Lowest fee in Australia! Only 5%. Buy and sell bitcoins quickly and easily! Cash deposit at any Westpac Bank and National Australia Bank branch in Australia.
|-
| [https://blockchain.info/wallet/deposit-methods Blockchain] ([[BlockChain.info|info]]) || USD, GBP, EUR, BRL, AUD, CAD, JPY, EUR, CHF, PLN, CZK, RON, RUB, SEK, NOK, DKK || Purchased through [[BitInstant]] (U.S., Brazil, and Russia), Barclay's Pingit or Bank Transfer (GBP), Instant Bank Transfer (EUR) or SMS or premium phone call from a mobile.
|-
| [[BitInstant]] || USD (Cash deposit at banks, 7-11, Walmart, CVS, Moneygram locations) USD (Dwolla) BRL (Cash deposit at Banco Rendimento or through Boleto) RUB (Cash deposit through Qiwi or Cyberplat) || Deposit cash at 700,000 locations around the world and have your Bitcoins within 30 minutes. Absolute fastest and easiest way to buy Bitcoins.
|-
| [[Coinapult]] || Use [[BitInstant]] to use cash to purchase bitcoins sent to e-mail or SMS. Choose "Bitcoin to e-mail" service and enter either e-mail or SMS. ||
|-
| [https://www.ripio.com/ Ripio] || Buy bitcoin in Argentina using cash payment networks like PagoFacil, RapiPago, etc. || A good option for bitcoin beginners transactions take usually less than 24 hours and places for doing the payments are all over.
|-
| [http://coinbase.com/?r=514b6eb6a18f2fdde50000db&utm_campaign=user-referral&src=referral-link Coinbase] || Buy and sell bitcoin by connecting a U.S. based bank account. Users need the account and routing numbers that can be found on a check to get started. || Instant verification available for new accounts. Purchased bitcoin can be held in Coinbase's online wallet. Generally considered a good option for U.S. based bitcoin beginners.
|-
| [[Coin-Daddy]] || Buy bitcoins with PayPal and OKPAY || No verification needed. Customer just needs to pay with PayPal, leave the Wallet address and then he receives his coins, or pays via OKPAY. Available for purchase are: Bitcoins, Litecoins and PPCoins.
|-
| [http://BitcoinIsrael.co.il BitcoinIsrael.co.il] || ILS (NIS - New Israeli Shekel)
* via bank transfer
* via Bank HaDoar /Post Office Bank (instant transfer)
* via In Person
|| Buy and sell your Bitcoins within minutes in person. Get "same day" service using Bank HaDoar /Post Office Bank. Get "next day" service using Bank Transfer.
|-
| [[Bitcoin Nordic]] ||
*EUR/DKK (SEPA and wire transfer)
*USD, EUR, GBP, DKK, SEK, NOK (Cash or check in the mail)
*AED, DZD, EGP, IQD, ILS, JOD, KWD, LGP, LYD, MRO, MYR, NGN, OMR, PKR, QAR, SAR, TRL, TZS, TND, YER ([[CashU]] card)
*MXN, EYU, BOB, BRL, COP, SYP, MAD, GHC, ZAR, CNY, CAD, and more ([[UKash]] voucher)
|| For UKash, redeemed through CashU account.
|-
| [[Spend Bitcoins]] || AUD (Cash deposit) || AUD cash deposit at NAB, Commonwealth Bank, Westpac and ANZ.
|-
| [https://bitcoinmylife.com/jml/buy-bitcoins BitcoinMyLife] ([[BitcoinMyLife|info]]) || EUR (SEPA bank transfer) || Simple and Safe. Pay first transaction fee with Twitter or Facebook post.
|-
| [[bitcoin.de]] || EUR (bank wire) EUR (SEPA bank transfer) EUR ([[Skrill]]/Moneybookers) || Varies (person to person) 0.01 free Bitcoins for every new user eWallet Affiliate program Language: German, Englisch News
|-
| [https://www.BitcoinZAP.com BitcoinZAP] || SEPA bank transfer - EUR International bank transfer - EUR, USD Western Union MoneyGram Cash (in the mail) - EUR, USD, CAD, GBP, HKD, JPY, PLN, AUD, CHF, CZK, DKK, HUF, MOP, SEK, NOK || Bitcoins usually delivered in less than 24 hours after payment is received
|-
| [[BTCX.se]] || SEK || Transfer to and banks in Sweden.
|-
| [[BTC China]] || || Converted to CNY for trading.
|-
| [[bitcoincambodia.com]] || USD (Cash, possible to pay everywhere in Cambodia) || You can buy Bitcoins for USD in Cambodia.
|-
| [[BitMarket.co]] || COP (Colombian Peso) || Varies (person to person)
|-
| [[bitcoin-otc|#bitcoin-otc]] || Person-to-person, various methods || IRC trading marketplace will usually have people willing to deal for small and larger amounts using various payment methods, including [[PayPal]], [[Dwolla]], [[Linden Dollars]], etc.
|-
| [[Canadian Bitcoins]] || CAD (Cash - XpressPost or Dropoff) USD (Cash - Courier: UPS, FedEx, etc.) || For dropoff, office in Ottawa.
|-
| [http://coinrepublic.com/buy-sell-bitcoins-singapore/ Coin Republic] || SGD (Singapore Dollar)|| Payment via local bank transfer.
|-
| [https://dgtmkt.com Dgtmkt] ([[Dgtmkt|info]]) || Malaysian Ringgit (MYR) Online bank transfers (Maybank2U, CIMB, MEPS, etc) E-vouchers (Web Cash, Mobile Money) || Bitcoin merchant for Malaysians,. dealing in Malaysian Ringgit. Fully automated immediate transfers. https://dgtmkt.com
|-
| [https://www.dagensia.eu Dagensia] ([[Dagensia|info]]) ||
* SEPA Bank Transfer (EUR)
* ATM card (EUR, USD)
* Sofort Banking (EUR)
* Direct Banking (EUR)
* Payza (official Exchanger)
* EgoPay, c-gold
* BUY AND SELL BITCOINS
|| Dagensia allows you to Buy and Sell Bitcoins and to store Bitcoins securely. You can get your first Bitcoin today, or you can start accepting Bitcoins directly into EUR or USD balance and ATM card. Sell and buy your Bitcoins through Wire, or SEPA EUR transfer, Direct Banking, ATM Cards. '''Fully licensed exchanger''', supervised by Czech National Bank
|-
| [[Lilion Transfer]] || Bank Transfer: USD, AUD, CAD, JPY, EUR, CHF, GBP, PLN, CZK, RON, BGN, HRK, RUB, SEK, NOK, DKK, LTL, LVL Perfect Money Monetto OK Pay Cosmic Pay Pecunix C-Gold E-Pay Payments PayPal|| 122 accounts worldwide. Support in 30 languages
|-
| [[Nanaimo Gold]] || Western Union money transfer Moneygram money transfer Cash in the mail || Digital Currency <--> Bitcoin exchange is automated For cash in the mail send USD, EUR, CAD, or GBP. Canada mailing address.
|-
| [[Bitcoin Argentina]] || Cash: ARS, BRL, USD Bank transfer: ARS || No exchange fees!
|-
| [[Bitcoin.com.es]] || EUR (bank deposit) || Bank transfer or cash deposits at OpenBank in Spain.
|-
| [[Bahtcoin]] || Cash, Webmoney || Will cash out to Thai mobile and gaming prepaid cards as well.
|-
| [http://bitcoin.in.th Bitcoin Thailand] || THB: Cash/Bank Deposit || Same day service.
|-
| [[BitPiggy]] || AUD (Australian Dollar)|| Payment via bank transfer.
|-
| [[bitcoin.local]] || Person-to-person, various methods ||
|-
| [[bcchanger.com]] || Person-to-person via PayPal, [[Skrill]]/Moneybookers and other e-currency platforms ||
|-
| [[Bitcoil]] || ILS (bank transfer) ||
|-
| [[File:BXlogoSM.jpeg|link=http://bitXoin.com]] [http://bitXoin.com bitXoin] ([[bitXoin|info]]) || AUD (Cash deposits) || Fast transaction processing, market rates with low commissions and no fees.
Contact BUYbulk@bitXoin.com for special rates on BUY BTC transactions over $10,000 and SELLbulk@bitXoin.com for SELL BTC transactions over BTC50
https://bitXoin.com/
|-
|[[btcnow]] || USD (OKPay, Dwolla) || bitcoins transferred instantly
|-
| [http://localbitcoins.com LocalBitcoins.com] || Varies (person to person) Physical cash locally [https://localbitcoins.com/buy-bitcoins-online/cash-deposit/ Cash deposit] [https://localbitcoins.com/buy-bitcoins-online/okpay/ OKPay] [https://localbitcoins.com/buy-bitcoins-online/paypal/ PayPal] [https://localbitcoins.com/buy-bitcoins-online/dwolla/ Dwolla] [https://localbitcoins.com/buy-bitcoins-online/sepa-eu-bank-transfer/ SEPA Bank transfer] || Find your local bitcoin dealer, or purchase safely online using escrow! With dynamic pricing with equations. eWallet 
[https://localbitcoins.com/affiliate/ Affiliate program] 
[https://localbitcoins.com/api-docs/ API]
|-
| [https://www.bitbuy.nl BitBuy] || EUR (iDEAL) || Buy bitcoins instantly with iDEAL from the Netherlands. User will get price updates during the payment process.
|-
| [https://www.happycoins.com HappyCoins] || EUR (iDEAL and SEPA bank transfer) || Buy and sell Bitcoins. Use the Dutch iDEAL payment system to receive Bitcoins within minutes. Prices are based on near real-time exchange prices.
|-
| [[ECurrencyZone]] || BTC INR (Cash deposit of Indian rupee) BDT (Cash deposit of Bangladeshi taka) NPR (Cash deposit of Nepalese rupee) MYR (Cash deposit of Malaysian ringitt) SGD (Cash deposit of Singaporean dollar) SGD (Net/Bank transfer) USD (Western Union, Moneygram, Citibank global funds transfer, OKPay) USD || Bank transfer considered at all locations with prior approval.
|-
| [[BitCoinVend]] || BTC USD (PayPal) || bitcoinvend@gmail.com, market variable with commission, quote based, verified paypal account with anti scammer verification
|-
| [[Bitcoins In Berlin]] || EUR (Cash in-the mail) EUR (Cash in-person trade) EUR (SEPA bank transfer) EUR (Western Union) || Cash in-the-mail is to a Berlin P.O. box. In-person trade is in Berlin.
|-
| [https://www.lojabitcoin.pt Loja Bitcoin] || EUR (ATM/Multibanco) EUR (bank transfer) EUR (money order) EUR (cash) || Several payment methods like the Portuguese "Multibanco" (ATM), "Vale postal CTT" (money order by mail), bank transfer and cash (in some locations) - Portugal only at the moment
|-
| [[Mang Sweeney]] || PHP (Cash) PHP (Cash deposit at bank) || Languages: English, Pinoy. PHP [https://localbitcoins.com/accounts/profile/mangsweeney cash trade method] in metro Manilla, Philappines.
|-
| [[mercaBit.eu]] || EUR (Ukash) EUR (Hal-Cash) EUR (Neteller) || Buy bitcoins with ukash and more
|-
| [http://buyBTC.cz buyBTC.cz] ([[buyBTC.cz|info]]) || CZK (Domestic bank transfer) EUR (Bank transfer) || Buy bitcoins from the Czech Republic.
|-
| [http://bitonic.nl Bitonic.nl] || EUR (iDeal) || Buy bitcoins instantly from the Netherlands.
|-
| [http://www.dragons.tl Dragon's Tale] ([[Dragon's Tale|info]]) || Credit card (except in the U.S.) || Purchase bitcoins through this MMO casino with credit card, withdraw bitcoins (though a fee applies if withdrawn and no casino play.)
|-
| [https://buybitcoinbycreditcard.com buybitcoinbycreditcard.com] || JPY (Credit Card) || Buy bitcoins instantly with your credit card. No registration required. This site accept from the world.
|-
| [[OKPAY]] || BTC USD, EUR, GBP, RUB, CHF etc (Bank Wire Transfer) EUR (SofortBanking) USD, EUR (Liqpay) USD (CashU) USD, EUR, GBP, RUB, CHF etc (UWCFS) USD, RUB, UAH (Wallet1) RUB (Yandex Money) RUB (EasyPay) USD, EUR (CONTACT) USD, EUR (Migom) USD, EUR, CZK (Money Polo) USD, EUR (Intel Express) USD, EUR (Western Union via Exchange Partners) USD, EUR (Moneygram via Exchange Partners) USD, EUR (via Exchange Partners) || Support of 19 world currencies, 15 languages.
|-
| [http://bitplaats.nl Bitplaats.nl] || EUR (iDEAL) || Buy bitcoins instantly, pay with iDEAL. Buy bitcoin from the Netherlands.
|-
| [http://artabit.com artaBit.com] ([[artaBit|info]]) || IDR || Buy bitcoins in Indonesia.
|-
| [https://www.bitsofgold.co.il BitsOfGold.co.il] ([[Bits_of_Gold|info]]) || ILS || Buy bitcoins from Israel.
|-
| [http://www.rugatu.com rugatu.com] || EUR || Buy bitcoins with Neteller.
|-
| [http://wmeng.exchanger.ru WMeng.Exchanger.ru] || Buy bitcoins with:<ul><li>USD</li></li>EUR</li></li>RUB</li></li>UAH</li></li>Belorussian Roubles</li></li>Vietnamese Dongs</li></ul> Sell bitcoins for:<ul><li>USD</li></li>EUR</li></li>RUB</li></li>UAH</li></li>Belorussian Roubles || The exchange service of WebMoney Transfer system. WMT has a special units named WMX to operate BTC, which can be exchanged and/or withdrawn
|-
| [[WM-Center]] || USD (Western Union, MoneyGram) EUR RUR THB UAH || 24/7/365 support English, Spanish, Russian versions Fast reliable service since 2005
|-
| [https://www.bitgo.co.il/ bitgo.co.il]|| ILS || Buy/Sell bitcoins in Israel.
|-
| [http://www.belgacoin.com Belgacoin]|| EUR, USD, BGN, CHF, CZK, DKK, EEK, GBP, GIP, HRK, HUF, ISK, LTL, LVL, NOK, PLN, RON, SEK || The easiest way to buy Bitcoins in Europe. It is fast, secure and cheap. No registration required!
|-
| [https://bittiraha.fi/content/bittip%C3%B6rssi-osta-ja-myy-bitcoineja Bittiraha.fi]|| EUR (SEPA transfer) || Reliable Finland based exchange operated since 2012. 1-2 day deposits and 1-3 day withdrawals. No registration required!
|-

| [https://bitalo.com Bitalo] ([[Bitalo|info]]) || Varies (person to person) [https://localbitcoins.com/buy-bitcoins-online/sepa-eu-bank-transfer/ SEPA Bank transfer] || Purchase Bitcoins directly from another person. eWallet
|}

==Direct / Bulk Buying==

Liquidity providers for transactions of size ($10,000 or larger).

{| class="wikitable"
|-
| Service || Type || Payment Method || Notes
|-
| [https://www.bitbrothersllc.com BitBrothers LLC] || Direct purchases up to $10,000 || USD (Bank Deposit at a Chase bank OR cash orders including cashiers checks and money orders) || BTC || Best customer service in the industry and quickest transaction speeds.
|-
| [http://bitcointalk.org/index.php?topic=87094.0 BitPay] ([[BitPay|info]]) || Direct purchases, $10,000 USD and higher || USD (Bank wire, domestic or international) || BTC || Contact for other payment methods.
|-
| [https://truckcoin.com TRUCK COIN] || Directly and Easily || USD, EUR, SGD, VND and more (Bank Wire, Western Union, Paypal, face-face) || BTC || Contact for other method directly with sellers or buyers.
|}

==Other Financial Services==

{| class="wikitable"
|-
| Service || Type || Payment || Settled || Notes
|-
| [https://giftcarddrainer.com GiftCardDrainer.com] || Transfer gift card balance to Bitcoin address or conventional account. || BTC, USD || || Customers can redeem their Visa, MasterCard, American Express or Discover gift card for Bitcoins or payment into their personal bank or PayPal account. 5.7% + $0.57 fee.
|-
| [http://www.indx.ru/?lang=en-US INDX] || Stock market, where BTC are also traded || - || - || Trader`s account can be withdrawn with BTC or with USD via WebMoney.
|-
| [[MPEx]] || Buy / Sell / Exercise CALLs / PUTs, American style. 52 strikes offered (by .5), current month + 2. No shorting available yet.|| BTC || BTC || Transactions encoded via amt. Must use non-rounding client (0.3.24 or later)
|-
| [https://vircurex.com/ Vircurex] || Buy / Sell Options Loan / Borrow || BTC, NMC, LTC, DVC, GG, I0C, IXC, SC || BTC, NMC, LTC, DVC, GG, I0C, IXC, SC ||
|}

==Physical Bitcoins==

Physical Bitcoins are bearer tokens that have an embedded redeemable digital bitcoin value if torn open. While they are somewhat expensive if bought purely for the digital bitcoins, they are relatively easy to get, because they can be purchased with PayPal or credit card - payment methods typically not accepted for pure digital bitcoin purchases.

{| class="wikitable"
|-
| Service || Type || Payment || Notes
|-
| [https://www.casascius.com Casascius.com] || Casascius Physical Bitcoins || BTC ||
|-
| [https://btcstore.eu BTCstore.eu]|| BTC Store Paperwallets, Casascius and Recalescence Physical Bitcoins reseller || BTC, EUR (SEPA bank transfer), Finnish online banks ||
|}

==Exchange Directories==
* [http://bitcoinx.io/ BitcoinX.io] Peer-to-Peer Bitcoin Reviews
* [http://howtobuybitcoins.info/ HowToBuyBitcoins.info]
* [http://wheretobuycryptocoins.com WhereToBuyCryptocoins.com]. Shows exchanges, markets, faucets, sites to spend cryptocoins and more.

==Bitcoin ATM==
As of June 2014 there are around 100 bitcoin ATM machines installed in the world. See [http://coinee.net/bitcoin-atm-manufacturers Coinee] for the list of locations.

==See Also==
* [[:Category:Digital_currencies|Digital Currencies]]
* [[Selling bitcoins]]
* [[Secure Trading]]
* [[Bitcoin Ladder]]
* [[:Category:Local|Local]] exchanges

[[Category:Exchanges]]
[[Category:Introduction]]
[[zh-cn:购买bitcoins]]
[[ru:Приобретение биткойнов]]