Wallet
A Bitcoin wallet contains[1]:
- your keypairs for each addresses
- transactions done from/to your addresses
- user preferences
- default key
- reserve keys
- accounts
- a version number
- Key pool
The data file for the wallet is wallet.dat and is located in the Bitcoin data directory.
It is intended that a wallet be used on only one installation of Bitcoin at a time. Attempting to clone a wallet for use on multiple computers will result in "weird behavior"[2].
