Bitcoin is a payment system introduced as open-source software in 2009 by developer Satoshi Nakamoto.
The payments in the system are recorded in a public ledger using its own unit of account, which is also called bitcoin.
Payments work peer-to-peer without a central repository or single administrator, which has led the US Treasury to call bitcoin a decentralized virtual currency.
Although its status as a currency is disputed, media reports often refer to bitcoin as a cryptocurrency or digital currency.
