Bitcoin is a worldwide cryptocurrency and digital payment system^[8]:3 called the first decentralized digital currency, as the system works without a central repository or single administrator.^[8]:1[9] It was invented by an unknown person or group of people under the name Satoshi Nakamoto^[10] and released as open-source software in 2009.^[11] The system is peer-to-peer, and transactions take place between users directly, without an intermediary.^[8]:4 These transactions are verified by network nodes and recorded in a public distributed ledger called a blockchain.

Bitcoins are created as a reward for a process known as mining. They can be exchanged for other currencies,^[12] products, and services. As of February 2015, over 100,000 merchants and vendors accepted bitcoin as payment.^[13] Bitcoin can also be held as an investment. According to research produced by Cambridge University in 2017, there are 2.9 to 5.8 million unique users using a cryptocurrency wallet, most of them using bitcoin.^[14]