Bitcoin is a software-based payment system released in 2009 by Satoshi Nakamoto as open source software. The payments in the system are recorded in a public ledger using its own unit of account, called bitcoin.

Payments operate on a peer-to-peer system without a central repository or single administrator. The U.S. Treasury calls bitcoin a decentralized, virtual currency. Media reports often refer to bitcoin as a “cryptocurrency” or “digital currency.”