A Bitcoin wallet is a collection of private keys but may also refer to client software used to manage those keys and to make transactions on the Bitcoin network.
This page covers various wallet formats in use.
The original Bitcoin client stores private key information in a file named wallet.dat following the so called "bitkeys" format.
- keypairs for each of your addresses
- transactions done from/to your addresses
- user preferences
- default key
- reserve keys
- a version number
- Key pool
- Since 0.3.21: information about the current best chain, to be able to rescan automatically when restoring from a backup.
It is intended that a wallet file be used on only one installation of Bitcoin at a time. Attempting to clone a wallet file for use on multiple computers will result in "weird behavior".
The format of this file is Berkeley DB. Tools that can manipulate wallet files include pywallet.
Bitcoin Wallet uses the bitcoinj protobuf format for its wallet file. However, due to Android isolation of applications, it is impossible to access the wallet file as a non-root user.
Denarium is Physical Bitcoin coin manufacturer. Denarium produces easy, handy and secure wallets in a coin form. The private key is stored under a security seal without password protection. Denarium also offers a trustless multisignature coins, which eliminates the need to trust the manufacturer.
Ledger Wallet manufactures various hardware wallets.
TREZOR is an isolated hardware environment for offline transaction signing and using a small display you can visually verify the transaction contents.
Opendime is a small USB stick that allows you to spend Bitcoin like a dollar bill. Pass it along multiple times. Connect to any USB to check balance. Unseal anytime to spend online. Trust no one.