Bitcoin Wiki - User contributions [en]

OpenCL miner

2011-06-02T18:10:36Z

Technowizard12:

An '''OpenCL miner''' is a bitcoin miner that uses the [http://en.wikipedia.org/wiki/OpenCL OpenCL framework] to perform the [[hash|hashing]] computations. When used with a modern GPU, this can produce hash rates orders of magnitude higher than what can be achieved with a CPU.

==Overview==

OpenCL is a computing framework which allows programmers to write code which works across a variety of hardware, both CPUs and GPUs included. OpenCL was originally developed by Apple.

The use of an OpenCL miner allows one to hash using a GPU (Graphics Processing Unit), which has a vastly larger ability to perform algorithmic calculations than an CPU (Central Processing Unit).

==Requirements==

Hashing on a GPU requires an OpenCL compatible ([http://developer.amd.com/gpu/AMDAPPSDK/pages/DriverCompatibility.aspx ATI/AMD]) or CUDA compatible ([http://www.nvidia.com/object/cuda_gpus.html NVIDIA]) graphics card.

The python [[Poclbm]] open source OpenCL bitcoin miner was created by m0mchil<ref>[http://www.bitcoin.org/smf/index.php?topic=1334.0 m0mchil's announcement on the forum]</ref> based on the open source CUDA client originally released by puddinpop<ref>[http://www.bitcoin.org/smf/index.php?topic=133.msg13135#msg13135 puddinpop's open source CUDA miner]</ref>.

Subsequently the java [[DiabloMiner]] based on m0mchil's was created by Diablo-D3<ref>[http://www.bitcoin.org/smf/index.php?topic=1721.0 Diablo's announcement on the forum]</ref>.

Puddinpop has also released a C++ OpenCL client capable of being compiled into the GUI client or daemon, or as a stand alone RPC miner<ref>[http://www.bitcoin.org/smf/index.php?topic=2444.0 puddinpop's RPC miners]</ref>.

Another miner was released by Jedi95 & CFSworks released [[Phoenix miner]]<ref>[http://www.bitcoin.org/smf/index.php?topic=6458.0 Jedi95 & CFSworks phoenix miner]</ref> which can work with memory underclocked to 300MHz and scans whole 2<sup>32</sup> nonce space.

See the [[Mining Hardware Comparison]] page for detailed statistics on the hash rates that can be achieved with various hardware.

==See Also==

* [[Mining hardware comparison]]
* [[:Category:Miners|Miners]]
* [http://www.bitcoin.org/smf/index.php?topic=4308.msg62882#msg62882 ATI Stream SDK] downloads
* [http://www.pcper.com/article.php?aid=745 ATI Stream vs. NVIDIA CUDA - GPGPU computing battle royale]
* [http://www.overclock.net/graphics-cards-general/363095-processing-cores-vs-stream-processing-units.html Processing Cores vs. Stream Processing Units]

==References==
<references/>

[[Category:Mining]]

Public relations

2011-06-01T06:11:29Z

Technowizard12:

'''Public relations''' is about how Bitcoin is presented to the world. The mathematical foundations of Bitcoin minimize the level of trust necessary to use it, but for anyone who isn't interested in cryptography the strength of the Bitcoin brand is more important.

This page lists some community-developed talking points, so if you'd like to promote Bitcoin consider using them.

==Terminology==

Bitcoin is technically a ''crypto-currency'', that is, a [[how bitcoin works | currency based on cryptography.]] However the crypto- prefix has another meaning, "something whose nature is obfuscated", as in cryptic messages. In that sense the term may not intuitively reflect the open source and community-based nature of the project. Also, cryptography is correctly perceived by many as a difficult and highly academic form of mathematics, which makes the term crypto-currency sound intimidating.

There are various alternatives, but many don't translate well into other languages or have other undesirable connotations.

'''Do say'''
* Bitcoin is an [[digital currency|internet currency.]] This is an accurate description and combines two everyday concepts people are familiar with.
* Bitcoin is a decentralized currency. This emphasizes the primary difference to regular, state backed currencies.
* Bitcoin is a predictable currency, stressing the open nature of the algorithms and number there will be
* Bitcoin is open source, demonstrating the community feeling of the currency
* Bitcoin is getting stronger every day. Try and mention news stories and the current [[MtGox]] rates.

'''Don't say'''
* Bitcoin is a crypto-currency, grassroots currency, "currency of the people" etc. All these are loaded terms that may color peoples perceptions or translate badly into other languages.

==Benefits==

Bitcoin has many benefits over more traditional payment systems. Many of them can be summed up in one word: flexibility. Everyone likes flexibility, as long as it isn't too hard to deal with.

'''Do say'''
* Bitcoins can be stored with a bank or financial institution just like existing currencies if you want, but you're free to explore alternatives right up to and including entirely bank-free operation. After the financial crisis, disillusionment with banks is widespread and this aspect may appeal to some (not all).
* Bitcoin can reduce the costs of everyday goods, by making the financial markets more competitive and eliminating the risk premium that credit card transactions entail.
* Bitcoin is fair: it's as easy for you to sell things as buy them. Contrast with most existing payment systems in which accepting payments is much harder than making them.
* Bitcoin has strong privacy: you should be able to choose who knows about your financial transactions. There are no statements mailed to you detailing your every financial move.
* Bitcoin makes it easier to sell things over the internet. Most people aren't familiar with the myriad difficulties in this seemingly simple task.

'''Don't say'''
* Bitcoin transactions are free. They usually are today, but there are a few cases where a small fee is required. And in future fees will play a larger role. It's hard to predict what level fees will end up at, as they are paying for something entirely different to existing systems. There are good reasons to believe Bitcoin transactions will always be cheaper than most financial transactions are today, but the arguments on this topic are complex.
* Bitcoin can't be taxed. Tax collectors were around before electronic payments and they'll be around after Bitcoin.
* Bitcoin is anonymous. [[Anonymity]] and Bitcoin is a complex topic, and anonymity means something slightly different to privacy.

==Politics and the law==

Bitcoin appeals to many libertarians, a political movement that emphasizes minimal government and individualism. If you are such a person, it's tempting to frame Bitcoin as some kind of anti-government force. But right or wrong many people are turned off by politics, and many others don't have an anti-government world view. This is especially true in Europe.

'''Do say'''
* Bitcoin is a chance to revolutionize the financial system, making it fairer and more democratic.
* Bitcoin offers a strong level of privacy, but the people you trade with still know who you are. If the police turn up with the right warrants, they will probably learn who owns particular addresses. This means lawbreakers can still be tracked down with sufficient effort. As an analogy you can use the internet itself - whilst the average person and even large corporations can't find out the real identity behind an IP address, the law can make everyone work together to identify the owner.
* Bitcoin allows anyone to pay anyone else. The authority to spend bitcoins belongs solely to the owner of the bitcoins. They decide and are responsible for the legality and morality of their actions, not a central authority.

'''Don't say'''
* Bitcoin is a way to topple or restrict the power of governments. None of the key project developers share this goal.
* Bitcoin is impossible to regulate or control. There are schemes in which by regulating miners, Bitcoins can be frozen much as assets are sometimes frozen today. It's hard to know if they will ever be implemented, but it's not the case that Bitcoin cannot be regulated.
* Bitcoin is going to be outlawed. There aren't any laws that would make Bitcoin obviously illegal, however, financial regulation is an extremely complex topic and it's possible that individual companies, exchanges etc, may at some point be found to not be in compliance. This happens to large, well-respected financial institutions so it's unreasonable to expect it will never happen to something Bitcoin related.

==Expectations==

Starting around the middle of 2010, Bitcoin has experienced dramatic growth in both the size of its community and exchange rates. People who are naturally optimistic or enthusiastic about Bitcoin sometimes try to promote it as a kind of get-rich-quick scheme.

'''Do say'''
* Bitcoin is an experiment that has grown rapidly as interest in the idea spreads.
* There are many people trading real goods and services with Bitcoins.
* Whilst the fundamental idea of Bitcoin is sound, pricing it is hard because nobody really knows the future potential. As a result the value swings wildly back and forth.
* Although speculation of Bitcoins' value is possible and many are doing it, hoarding coins is an extremely risky investment strategy. Like many risky investments, it has potentially high returns but you could also lose everything.
* Whilst Bitcoin might fail, the concept of internet currencies is here to stay.

'''Don't say'''
* Bitcoins value has only gone up. Whilst the long term trend has been up, exchange rates are highly volatile and go down frequently.
* Get in now before it's too late. This makes Bitcoin sound like a scam.
* Bitcoin will take over the world unless <foo>. There are many potential end-games for Bitcoin of which "taking over the world" or "absolute failure" are only two. It could just as easily end up stuck in a niche, becoming an established competitor in the internet payments space but not going beyond that, etc.

==Economics==

Bitcoin uses a simple and easy to understand economic model, that is quite different to the one used by regular state-backed currencies today. Many people who just want to use the currency won't be interested in this aspect of the system. If they are:

'''Do say'''
* Bitcoin is intended to have a stable quantity of coins in existence in the long run.
* Bitcoin inflates rapidly at present because the system is young. Over many decades, inflation will slow and eventually stop.
* Assuming the (Bitcoin using) economy grows, that means that after some decades of operation, the value of a single Bitcoin will increase at roughly the same rate as the economy itself.
* A growing economy with a static currency behaves, to the end user, much like a growing economy in which you put your money into an interest-bearing account. The value increases slowly over time, but you can usually earn more by investing in higher-risk ventures.
* If it comes up, the usual formulation of the deflationary spiral argument (people won't spend money because it's always worth more tomorrow) is over-simplified. Consider consumer electronics, in which waiting a few months practically guarantees you something better for the same money. The actual economic argument, which is valid, has to do with the way existing currencies are expanded via the issuance of debt. Bitcoins are not issued via loans so the argument doesn't apply in the same way.

'''Don't say'''
* Bitcoin is deflationary. This implies the total amount of currency is intended to shrink. After inflation eventually shuts down, the currency will shrink at a very slow rate due to natural erosion, ie, people losing their wallet files due to failed hardware and missing backups (or simply losing interest and exiting the system). But this is better described as unavoidable than intentional.
* There are 21 million coins. The Bitcoin definition of a coin is very unintuitive: it's a unit that can be divided into 100,000,000 pieces. If you want to discuss the exact limit, be sure to clarify that whilst we talk about "bitcoins", the placement of the decimal point is arbitrary and was chosen for convenience.

==Notes and Addenda==

It should be noted that the way you present the currency greatly depends on your audience. If the person you are speaking to is not an anarchist or anyone too much into anonymity, don't mention these aspects of the community. Tailor the way you present the currency to the interests of the audience.

''e.g. Do not mention that you can buy all sorts of drugs untraceably at a geriatric knitting convention''

==See Also==

* [[:Category:Marketing|Marketing]]

[[Category:Marketing|Marketing]]

Distributed miner

2011-06-01T05:15:51Z

Technowizard12: Created page with "{{stub}} A distributed miner is a Bitcoin miner made from the pooled efforts of multiple computers, possibly without the computer user's knowledge. ==Overview== Usually, the t..."

{{stub}}

A distributed miner is a Bitcoin miner made from the pooled efforts of multiple computers, possibly without the computer user's knowledge.

==Overview==

Usually, the theory behind distributed miners consists of dividing work into workunits and sending them to various computers, who all report back with their work to be submitted en masse by a central processor. Alternatively, though, the computers can coordinate themselves to submit without any central puppetmaster.

==Distributed Miners in the Wild==

[[Stealthcoin]] employs a method not unlike this, where unused computers act as bitcoin miners. It currently does not, however, coordinate between bots.

[[Bitp.it]] uses distributed mining through a small bit of javascript running on browsers viewing a website

[[Bitcoin Plus]] allows the distributing of works amongst friends using their client, or through an embeddable website script

==See Also==

* [[Stealthcoin]]

* [[Bitp.it]]

* [[Bitcoin Plus]]

Bitp.it

2011-06-01T05:10:13Z

Technowizard12:

Bitp.it is an embedable Javascript Bitcoin Miner which creates a [[Distributed Miners| Distributed Miner]] through sending workunits to different browsers viewing a webpage.

==Overview==

To use Bitp.it, the user signs up on the homepage. They then are sent a customized javascript script to embed in the <head> section of their webpage. This then uses the browser of users viewing the webpage as a [[CPU Miner]], pooling the distributed resources to earn Bitcoins through [[Bitcoin Pooled Mining|Slush's Pool]].

==History==

The project was announced on the [http://forum.bitcoin.org/index.php?topic=9042.msg130817#msg130817 Bitcoin Forum] on May 20, 2011 by 1bitc0inplz, one of the lead developers.

The project, met with resounding approval, soon gained a better UI and more features such as an overview of the performance of all sites, the ability to change your wallet, and a view of the current balance.

==See Also==

* [[Distributed Miners]]

* [[Browser Bitcoin Miner]]

* [[CPU Miner]]

==External Links==
* [http://bitp.it Bitp.it]

* [http://forum.bitcoin.org/index.php?topic=9042.msg130817#msg130817 Forum Announcement]

Bitp.it

2011-06-01T05:09:19Z

Technowizard12: Created page with "Bitp.it is an embedable Javascript Bitcoin Miner which creates a Distributed Miner through sending workunits to different browsers viewing a webpage. ==O..."

Bitcoin Plus

2011-06-01T04:57:35Z

Technowizard12: Created page with "Bitcoin Plus is a Browser Bitcoin Miner written in Java. The miner is initiated by the end user, but is also embeddable in webpages, much like Bitp.it ==Overview== The ..."

Bitcoin Plus is a [[Browser Bitcoin Miner]] written in Java. The miner is initiated by the end user, but is also embeddable in webpages, much like [[Bitp.it]]

==Overview==

The user registers an account, then is prompted to start mining. Mining is paid on a pay-per-share basis, with 3% taken by the pool operators. The site suggests that users invite their friends to mine with them, and allows users to embed java miners on their websites to create a [[Distributed Miners|Distributed Miner]].

The UI provides features which seem to be exclusive to the site, such as a prediction of the time it will take to calculate one share.

This miner is a [[CPU Miner]]

==See Also==

* [[Bitp.it]]

* [[Distributed Miners]]

* [[CPU Miner]]

* [[Browser Bitcoin Miner]]

==External Links==

* http://www.bitcoinplus.com/

Browser Bitcoin Miner

2011-06-01T04:50:09Z

Technowizard12:

Browser based mining is the practice of utilizing web browsers as bitcoin miners through means of plugins or scripts.

== Introduction ==

This concept was first reached by Bitcoin Plus, a [[cpu-miner|cpu miner]] that is launched from the browser, requires no installation, and runs as a Java application. Additionally, this approach was done by [[Bitp.it|Bitp.it]] as javascript which is designed to be embeddable in webpages to create a distributed server farm.

==[[Bitcoin Plus|Bitcoin Plus]] Implementation==

The miner connects to a pool and the payout method is pay-per-share. The pool's fee is 3%.

Requires Java 1.5 or higher. This miner app is not open source.

This software was announced on May 18, 2011<ref>[http://forum.bitcoin.org/index.php?topic=8780.0 Browser Bitcoin Miner (No setup, no download, no configuration)]</ref>.

==[[Bitp.it|Bitp.it]] Implementation==

A user's computer is used by the website they are viewing, which has added Javascript to the <head> section of the site, as a distributed miner. [[Bitcoin Pooled Mining|Slush's pool]] is used as the pool which the distributed computer connects to.

==See Also==

* [[Why a GPU mines faster than a CPU]]

* [[Bitp.it]]

==External Links==

* [http://www.bitcoinplus.com http://bitcoinplus.com] web site

==References==
<references />

[[Category:Miners]]

Browser Bitcoin Miner

2011-06-01T04:46:56Z

Technowizard12: Made article general to all browser mining

==Overview==
This concept was first reached by Bitcoin Plus, a [[cpu-miner|cpu miner]] that is launched from the browser, requires no installation, and runs as a Java application. Additionally, this approach was done by [[Bitp.it|Bitp.it]] as javascript which is designed to be embeddable in webpages to create a distributed server farm.

==[[Bitcoin Plus|Bitcoin Plus]] Implementation==

The miner connects to a pool and the payout method is pay-per-share. The pool's fee is 3%.

Requires Java 1.5 or higher. This miner app is not open source.

This software was announced on May 18, 2011<ref>[http://forum.bitcoin.org/index.php?topic=8780.0 Browser Bitcoin Miner (No setup, no download, no configuration)]</ref>.

==[[Bitp.it|Bitp.it]] Implementation==

A user's computer is used by the website they are viewing, which has added Javascript to the <head> section of the site, as a distributed miner. [[Bitcoin Pooled Mining|Slush's pool]] is used as the pool which the distributed computer connects to.

==See Also==

* [[Why a GPU mines faster than a CPU]]

* [[Bitp.it]]

==External Links==

* [http://www.bitcoinplus.com http://bitcoinplus.com] web site

==References==
<references />

[[Category:Miners]]

Help:Introduction

2011-05-31T05:38:14Z

Technowizard12: /* Anonymity */

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

==Basic Concepts==

===Currency===

Alice is far away from Bob and wants to buy his [http://www.grasshillalpacas.com/alpacaproductsforbitcoinoffer.html Alpaca socks]. In return, she wants to send him a dollar. A dollar bill is a piece of paper which is very easy to create (by those who can), but which is accepted by people in exchange for valuable products and services in the real world, such as the socks Alice wants to buy. One simple thing Alice can do is to put a dollar bill in an envelope, mail it to Bob, and then wait for Bob to send the socks to her.

===Banks===

Another thing Alice can do is to "wire" the money to Bob. She can do that by first giving her dollar bills to an institution called a bank, the job of which is to safe-keep Alice's dollar bills and, in return, to give Alice a written promise (called a "bank statement") that, whenever she wishes, she can come to the bank to take back the same number of dollar 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 "giving" the dollar bills to Bob instead of her. This could be done by sending a person to Bob's door, with Alice's dollar bills in hand (or, better, fresh new dollar bills, if Alice's dollar bills are in bad condition), but usually it 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 in his next statement, or, if he is in a hurry, the next time he contacts his bank asking about how much money they have for him.

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 job of these machines is to learn what each customer wants to do with his/her money and, to the extent that it's possible, act on what the customer wants (for example, ATMs can hand cash). In the end, there is very little human involvement in this process, most of the time. The people can always know how much money out of the money that the bank is safe-keeping is theirs, and they are confident that the numbers they see in their bank statements and on their computer screens stand for the number of dollar bills that they can get from the bank at any time they wish. They can be so sure of that, that they can accept those numbers in the same way they accept paper dollars (this is similar to the way people started accepting paper dollars as they accepted gold or silver).

However, the fact that machines are used does not change the structure of this system, which is, as it was, based on a central authority (the bank) which is responsible for keeping records about how much money belongs to whom. Everybody has to rely on this central authority to be honest (i.e. to say the truth about how much money they are safe-keeping in total, or at least to make the paper money available upon demand from the owners). Also, every person has to identify him/herself to this authority, by giving his/her real name, in order to be allowed to get their paper bills back or to send money to another person.

Bitcoin is a system of owning and voluntarily transferring amounts of so-called bitcoins, in a manner similar to an on-line banking interface, but anonymously and without reliance on a central authority to decide on what is true. These bitcoins are valuable because they require the spending of real resources (CPU time and electricity) to produce, cannot be spent more than once, and cannot be removed from a person's ownership without illicit access to his/her computer.

==Bitcoin Basics==

===Preventing stealing===
To guarantee that an eavesdropper, Eve, cannot access other people's bitcoins by creating transactions in their names we use a [[Wikipedia:Public-key_cryptography|public key system]] to make digital signatures. In this system, each person, such as Alice and Bob, has a pair of public and private keys which he/she stores in a safe [[Wallet|wallet]]. Only the user with his secret private key can sign a document, such as the transaction to give some of his bitcoins to somebody else, but any one can validate the signature using the user’s public key.

* Bob sends his public key to Alice.
* Alice adds Bob’s public key along with the amount she wants to transfer, to the transaction.
* Alice signs the transaction with her secret private key.

As a result, anyone who knows the public keys of both Alice and Bob can now see that Alice agreed to transfer the amount to Bob, because nobody other than Alice 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 balance.

Later on, when Bob will transfer the same coins to Charley, he will do the same thing: receive from Charley his public key, add a new transaction to the chain of transactions and sign it with his (Bob) private key. But only Bob can do this, because only Bob has the private key which is necessary for signing and which is the only private key to match Bob’s public key that is already in the chain.

Eve cannot change who the coins belong to by replacing Bob’s public key with her public key, because Alice signed the transfer to Bob using her private key, declaring that the coins which belonged to her now belong to Bob, and Alice's private key is kept secret from Eve. So if Charley 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===
This is how we guarantee that Alice cannot replicate the coin and use it in more than one transaction (this is the main 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 will be permanently recorded, preventing Alice from creating a second transaction with the same coin.

In theory, Alice could attempt to generate spoofed blocks in which her past usage of the same coin does not appear and try to send these blocks to everyone as evidence that the coin is still hers. However, that past transaction, which contains a signature from Alice, has already been announced, has already been distributed to a very large number of computers in the bitcoin network and a block containing it has already been generated by someone (otherwise, the first receiver of the coin would have no confirmation). Since the process of generating a valid block is designed to take a [[Proof_of_work|long time]], Alice will be unable to compete with all these computers in the rate at which she can generate blocks. Bob will receive many more blocks from third persons than Alice alone will ever be able to generate, and some of the newer blocks will contain Alice's previous transaction, telling Bob that Alice has already spent her coin. The only way for Alice to remove her transaction is to create a parallel chain which is longer than the one generated by everybody else and which doesn't contain her transaction, as only the longest chain is accepted. To remain the longest, it also has to grow faster than any other chain, so as to prevent any block generator from adding Alice's transaction to the chain. To do that, Alice has to be in a position to permanently command the majority of the CPU power on the network; something we assume no single person or organization can do. Therefore, as long as the people who control a majority of the CPUs are not cooperating with Alice, her transaction will be permanently recorded and she will be unable to create another transaction with the same coin.

===Anonymity===
Bitcoin "accounts" do not have people's names on them and do not have to correspond to individuals. Each balance is simply associated with a randomly generated public-private key pair and the money "belongs" to whoever has the private key and can sign transactions with it. The transactions that are signed using those keys also don't have to include names.

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

:15VjRaDX9zpbA8LVnbrCAFzrVzN7ixHNsC

Each person can have many such addresses, each with its own balance, and this can make it more difficult to identify which person owns what amount. In order to protect his [[Anonymity|privacy]], Bob can even generate a new public-private key pair for each individual transaction. So David receiving the coin from Charley will not be able to identify who is the second person in the list of transactions (not without asking Charley).

===Creation of coins===
As we saw, both Bob and Charley need to verify that the original coin from Alice is valid. Alice cannot simply generate coins instantly, out of thin air, because the appearance of a coin is a transaction that needs to be accepted by others.

According to current software, the way that new coins are slowly introduced is this: every computer that manages to generate a block is allowed to put one transaction there in which it gains 50 BTC, without this amount having to come from somewhere. This amount is an incentive for people to perform the computation work required for block generation. However, it is currently agreed that the reward for generating a block will be reduced to half every 4 years. Meaning that, at some point in the year 2013, the majority of the CPUs will stop accepting blocks in which the generating transaction adds 50BTC to the sum of money, and they will only accept blocks adding half that amount. The same thing will happen in the years 2017, 2021, 2025 and so on, unless different Bitcoin client software has prevailed in the network.

Since this incentive will eventually diminish, another way for Alice to gain bitcoins when she generates blocks is to accept [[Transaction_fee|transaction fees]]. There is a voluntary transaction fee that can be paid in every transfer of bitcoins, the amount of which is chosen, and paid, by the person who sends the money. This amount is given to the person who generates the "proof-of-work" block in which the transaction appears, which is necessary for the transaction to be accepted. Since Alice is free to include in her block whichever set of transactions she wants, she can choose to include only the transactions with the highest transaction fees. If everybody acts that way, then eventually, and depending on the total number of transactions, a minimum transaction fee will be required for a transaction to appear in the chain of blocks.

==Putting it all together==
Directly experience the system in action by visiting [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, should be around 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, drill into one of these blocks.
Start by noticing that the block's [[hash|hash]] begins with a run of zeros, this is what made making it so difficult.
The computer that generated this block had to run on many ''Nonce'' values (also listed on the block's page) until it found one that generated this run of zeros.
Next notice 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 notice 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 fee collected from other transactions in the same block.

Drill into any of the transactions and you will see how it is made from one or more amounts coming in and out.
The fact that there can be more than one incoming and outgoing amounts, allow the system to join and break amounts in any possible way allowing for any fractional amount needed (usually cents.)
Each incoming amount is a transaction from the past (which you can also drill to) coming from an address of someone
and each outgoing amount is addressed to someone and will be part of a future transaction (which you can also drill too if it also had already taken place.)

Finally you can drill into any of the [[Address|addresses]] and see what public information is available.

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

''So that all sounds good! How do I help? [[Helping Bitcoin|How to help Bitcoin]]''

==See Also==

* [http://www.youtube.com/watch?v=Um63OQz3bjo What is Bitcoin?] video introduction
* Installing Bitcoin [[getting started]]
* [[How bitcoin works]]
* [[Using Bitcoin]]
* A gentle introduction to Bitcoin - [[BitcoinMe]]
* Another introduction, ''The Rebooting Of Money'' podcast is found at [[Bitcoin Money]]

[[zh-cn:简介]]

[[de:Einführung]]

Help:Introduction

2011-05-31T05:37:46Z

Technowizard12:

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

==Basic Concepts==

===Currency===

Alice is far away from Bob and wants to buy his [http://www.grasshillalpacas.com/alpacaproductsforbitcoinoffer.html Alpaca socks]. In return, she wants to send him a dollar. A dollar bill is a piece of paper which is very easy to create (by those who can), but which is accepted by people in exchange for valuable products and services in the real world, such as the socks Alice wants to buy. One simple thing Alice can do is to put a dollar bill in an envelope, mail it to Bob, and then wait for Bob to send the socks to her.

===Banks===

Another thing Alice can do is to "wire" the money to Bob. She can do that by first giving her dollar bills to an institution called a bank, the job of which is to safe-keep Alice's dollar bills and, in return, to give Alice a written promise (called a "bank statement") that, whenever she wishes, she can come to the bank to take back the same number of dollar 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 "giving" the dollar bills to Bob instead of her. This could be done by sending a person to Bob's door, with Alice's dollar bills in hand (or, better, fresh new dollar bills, if Alice's dollar bills are in bad condition), but usually it 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 in his next statement, or, if he is in a hurry, the next time he contacts his bank asking about how much money they have for him.

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 job of these machines is to learn what each customer wants to do with his/her money and, to the extent that it's possible, act on what the customer wants (for example, ATMs can hand cash). In the end, there is very little human involvement in this process, most of the time. The people can always know how much money out of the money that the bank is safe-keeping is theirs, and they are confident that the numbers they see in their bank statements and on their computer screens stand for the number of dollar bills that they can get from the bank at any time they wish. They can be so sure of that, that they can accept those numbers in the same way they accept paper dollars (this is similar to the way people started accepting paper dollars as they accepted gold or silver).

However, the fact that machines are used does not change the structure of this system, which is, as it was, based on a central authority (the bank) which is responsible for keeping records about how much money belongs to whom. Everybody has to rely on this central authority to be honest (i.e. to say the truth about how much money they are safe-keeping in total, or at least to make the paper money available upon demand from the owners). Also, every person has to identify him/herself to this authority, by giving his/her real name, in order to be allowed to get their paper bills back or to send money to another person.

Bitcoin is a system of owning and voluntarily transferring amounts of so-called bitcoins, in a manner similar to an on-line banking interface, but anonymously and without reliance on a central authority to decide on what is true. These bitcoins are valuable because they require the spending of real resources (CPU time and electricity) to produce, cannot be spent more than once, and cannot be removed from a person's ownership without illicit access to his/her computer.

==Bitcoin Basics==

===Preventing stealing===
To guarantee that an eavesdropper, Eve, cannot access other people's bitcoins by creating transactions in their names we use a [[Wikipedia:Public-key_cryptography|public key system]] to make digital signatures. In this system, each person, such as Alice and Bob, has a pair of public and private keys which he/she stores in a safe [[Wallet|wallet]]. Only the user with his secret private key can sign a document, such as the transaction to give some of his bitcoins to somebody else, but any one can validate the signature using the user’s public key.

* Bob sends his public key to Alice.
* Alice adds Bob’s public key along with the amount she wants to transfer, to the transaction.
* Alice signs the transaction with her secret private key.

As a result, anyone who knows the public keys of both Alice and Bob can now see that Alice agreed to transfer the amount to Bob, because nobody other than Alice 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 balance.

Later on, when Bob will transfer the same coins to Charley, he will do the same thing: receive from Charley his public key, add a new transaction to the chain of transactions and sign it with his (Bob) private key. But only Bob can do this, because only Bob has the private key which is necessary for signing and which is the only private key to match Bob’s public key that is already in the chain.

Eve cannot change who the coins belong to by replacing Bob’s public key with her public key, because Alice signed the transfer to Bob using her private key, declaring that the coins which belonged to her now belong to Bob, and Alice's private key is kept secret from Eve. So if Charley 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===
This is how we guarantee that Alice cannot replicate the coin and use it in more than one transaction (this is the main 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 will be permanently recorded, preventing Alice from creating a second transaction with the same coin.

In theory, Alice could attempt to generate spoofed blocks in which her past usage of the same coin does not appear and try to send these blocks to everyone as evidence that the coin is still hers. However, that past transaction, which contains a signature from Alice, has already been announced, has already been distributed to a very large number of computers in the bitcoin network and a block containing it has already been generated by someone (otherwise, the first receiver of the coin would have no confirmation). Since the process of generating a valid block is designed to take a [[Proof_of_work|long time]], Alice will be unable to compete with all these computers in the rate at which she can generate blocks. Bob will receive many more blocks from third persons than Alice alone will ever be able to generate, and some of the newer blocks will contain Alice's previous transaction, telling Bob that Alice has already spent her coin. The only way for Alice to remove her transaction is to create a parallel chain which is longer than the one generated by everybody else and which doesn't contain her transaction, as only the longest chain is accepted. To remain the longest, it also has to grow faster than any other chain, so as to prevent any block generator from adding Alice's transaction to the chain. To do that, Alice has to be in a position to permanently command the majority of the CPU power on the network; something we assume no single person or organization can do. Therefore, as long as the people who control a majority of the CPUs are not cooperating with Alice, her transaction will be permanently recorded and she will be unable to create another transaction with the same coin.

==Anonymity==
Bitcoin "accounts" do not have people's names on them and do not have to correspond to individuals. Each balance is simply associated with a randomly generated public-private key pair and the money "belongs" to whoever has the private key and can sign transactions with it. The transactions that are signed using those keys also don't have to include names.

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

:15VjRaDX9zpbA8LVnbrCAFzrVzN7ixHNsC

Each person can have many such addresses, each with its own balance, and this can make it more difficult to identify which person owns what amount. In order to protect his [[Anonymity|privacy]], Bob can even generate a new public-private key pair for each individual transaction. So David receiving the coin from Charley will not be able to identify who is the second person in the list of transactions (not without asking Charley).

===Creation of coins===
As we saw, both Bob and Charley need to verify that the original coin from Alice is valid. Alice cannot simply generate coins instantly, out of thin air, because the appearance of a coin is a transaction that needs to be accepted by others.

According to current software, the way that new coins are slowly introduced is this: every computer that manages to generate a block is allowed to put one transaction there in which it gains 50 BTC, without this amount having to come from somewhere. This amount is an incentive for people to perform the computation work required for block generation. However, it is currently agreed that the reward for generating a block will be reduced to half every 4 years. Meaning that, at some point in the year 2013, the majority of the CPUs will stop accepting blocks in which the generating transaction adds 50BTC to the sum of money, and they will only accept blocks adding half that amount. The same thing will happen in the years 2017, 2021, 2025 and so on, unless different Bitcoin client software has prevailed in the network.

Since this incentive will eventually diminish, another way for Alice to gain bitcoins when she generates blocks is to accept [[Transaction_fee|transaction fees]]. There is a voluntary transaction fee that can be paid in every transfer of bitcoins, the amount of which is chosen, and paid, by the person who sends the money. This amount is given to the person who generates the "proof-of-work" block in which the transaction appears, which is necessary for the transaction to be accepted. Since Alice is free to include in her block whichever set of transactions she wants, she can choose to include only the transactions with the highest transaction fees. If everybody acts that way, then eventually, and depending on the total number of transactions, a minimum transaction fee will be required for a transaction to appear in the chain of blocks.

==Putting it all together==
Directly experience the system in action by visiting [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, should be around 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, drill into one of these blocks.
Start by noticing that the block's [[hash|hash]] begins with a run of zeros, this is what made making it so difficult.
The computer that generated this block had to run on many ''Nonce'' values (also listed on the block's page) until it found one that generated this run of zeros.
Next notice 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 notice 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 fee collected from other transactions in the same block.

Drill into any of the transactions and you will see how it is made from one or more amounts coming in and out.
The fact that there can be more than one incoming and outgoing amounts, allow the system to join and break amounts in any possible way allowing for any fractional amount needed (usually cents.)
Each incoming amount is a transaction from the past (which you can also drill to) coming from an address of someone
and each outgoing amount is addressed to someone and will be part of a future transaction (which you can also drill too if it also had already taken place.)

Finally you can drill into any of the [[Address|addresses]] and see what public information is available.

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

''So that all sounds good! How do I help? [[Helping Bitcoin|How to help Bitcoin]]''

==See Also==

* [http://www.youtube.com/watch?v=Um63OQz3bjo What is Bitcoin?] video introduction
* Installing Bitcoin [[getting started]]
* [[How bitcoin works]]
* [[Using Bitcoin]]
* A gentle introduction to Bitcoin - [[BitcoinMe]]
* Another introduction, ''The Rebooting Of Money'' podcast is found at [[Bitcoin Money]]

[[zh-cn:简介]]

[[de:Einführung]]

Bitcoin Market

2011-05-31T05:30:57Z

Technowizard12:

The '''Bitcoin Market''' is a [[bitcoin]] [[currency exchange]] site owned and operated by dwdollar. It supports [[PayPal]], Moneybookers, [[Pecunix]], and [[Liberty Reserve]]. Registration is open to the public. Unlike [[MtGox]], exchanges are done directly between individual users, with Bitcoin Market escrowing the bitcoin funds. Quite often, Bitcoin Market trades at higher values than MtGox.

==Use of the Market==

Those wishing to use the market must [https://www.bitcoinmarket.com/process/signup/create/ create an account]. One registers payment processors through the ''Accounts'' page. This is a necessary step for trading currency.

In order to trade, one must either open a bid through ''my orders''. Bids are made by declaring how much of a given currency you wish to buy and at what price. Bids can be accepted through the ''my trades'' page.

==History==

Trading on the site began February 6th, 2010<ref>[http://www.bitcoin.org/smf/index.php?topic=20.msg265#msg265 Announcement by dwdollar]</ref>

A major update to the site occurred in March, 2011. Among the changes were: smaller minimum trade size, 24 X 7 trading, and some steps to help ensure that payment will be made for trades that execute.

Important information can also be gained from the Bitcoin Market website homepage which shows a graph of the Bitcoin exchange rate (to US Dollars). This data is also offered in the JSON format.

==See Also==

* [[Buying bitcoins]]

==External Links==

* [https://www.bitcoinmarket.com/ Bitcoin Market]

==References==
<References />

[[Category:Exchanges]]

Bitcoin Market

2011-05-31T05:30:39Z

Technowizard12:

{{stub}}

The '''Bitcoin Market''' is a [[bitcoin]] [[currency exchange]] site owned and operated by dwdollar. It supports [[PayPal]], Moneybookers, [[Pecunix]], and [[Liberty Reserve]]. Registration is open to the public. Unlike [[MtGox]], exchanges are done directly between individual users, with Bitcoin Market escrowing the bitcoin funds. Quite often, Bitcoin Market trades at higher values than MtGox.

==Use of the Market==

Those wishing to use the market must [https://www.bitcoinmarket.com/process/signup/create/ create an account]. One registers payment processors through the ''Accounts'' page. This is a necessary step for trading currency.

In order to trade, one must either open a bid through ''my orders''. Bids are made by declaring how much of a given currency you wish to buy and at what price. Bids can be accepted through the ''my trades'' page.

==History==

Trading on the site began February 6th, 2010<ref>[http://www.bitcoin.org/smf/index.php?topic=20.msg265#msg265 Announcement by dwdollar]</ref>

A major update to the site occurred in March, 2011. Among the changes were: smaller minimum trade size, 24 X 7 trading, and some steps to help ensure that payment will be made for trades that execute.

Important information can also be gained from the Bitcoin Market website homepage which shows a graph of the Bitcoin exchange rate (to US Dollars). This data is also offered in the JSON format.

==See Also==

* [[Buying bitcoins]]

==External Links==

* [https://www.bitcoinmarket.com/ Bitcoin Market]

==References==
<References />

[[Category:Exchanges]]

User:Technowizard12

2011-05-31T05:23:05Z

Technowizard12:

Hiya, I'm Simon.

I do web, graphic, and UI design, along with content writing. See [http://www.simonorrstudio.com Simon Orr Studio] for my portfolio.

I'm a student, so my rates are reasonable. I've been taking design classes since 6th grade. I've studied aesthetics on my own time, in the psychological sense, and have a working knowledge of the theory behind it.

I've been using the internet all my life, so I know how pages should function to retain interest and maintain usability.

email me at simon@simonorrstudio.com if you want to talk, commission me, or need a consult.

Contributors Award participant: 1G41YpzPiQ9q2WwQ7HEWgFBoiYwy1Q3XRt

[[Category:Freelancers]]
[[Category:Freelancers-Graphic Design]]
[[Category:Freelancers-Web Design]]
[[Category:Freelancers-UI Design]]

Category:Freelancers-UI Design

2011-05-28T03:13:39Z

Technowizard12: Created page with "==See Also== * Freelancers-Web Design Category:Freelancers"

==See Also==

* [[:Category:Freelancers-Web_Design|Freelancers-Web Design]]

[[Category:Freelancers]]

User:Technowizard12

2011-05-28T03:12:49Z

Technowizard12:

Hiya, I'm Simon.

I do web, graphic, and UI design, along with content writing. See [http://www.simonorrstudio.com Simon Orr Studio] for my portfolio.

I'm a student, so my rates are reasonable. I've been taking design classes since 6th grade. I've studied aesthetics on my own time, in the psychological sense, and have a working knowledge of the theory behind it.

I've been using the internet all my life, so I know how pages should function to retain interest and maintain usability.

email me at simon@simonorrstudio.com if you want to talk, commission me, or need a consult.

[[Category:Freelancers]]
[[Category:Freelancers-Graphic Design]]
[[Category:Freelancers-Web Design]]
[[Category:Freelancers-UI Design]]

User:Technowizard12

2011-05-28T03:11:49Z

Technowizard12:

User:Technowizard12

2011-05-28T03:08:42Z

Technowizard12:

User:Technowizard12

2011-05-28T03:08:24Z

Technowizard12: Created page with "Hiya, I'm Simon. I do web, graphic, and UI design, along with content writing. See [http://www.simonorrstudio.com Simon Orr Studio] for my portfolio. I'm a student, so my rates..."

Hiya, I'm Simon.

I do web, graphic, and UI design, along with content writing. See [http://www.simonorrstudio.com Simon Orr Studio] for my portfolio.

I'm a student, so my rates are reasonable. I've been taking design classes since 6th grade. I've studied aesthetics on my own time, in the psychological sense, and have a working knowledge of the theory behind it.

I've been using the internet all my life, so I know how pages should function to retain interest and maintain usability.

email me at simon@simonorrstudio if you want to talk, commission me, or need a consult.