Bitcoin is a decentralized digital currency, without a central bank or single administrator, that can be sent from user to user on the peer-to-peer bitcoin network without the need for intermediaries. Transactions are verified by network nodes through cryptography and recorded in a public distributed ledger called a blockchain. Bitcoin is unique in that there are a finite number of them: 21 million.

Bitcoins are created as a reward for a process known as mining. They can be exchanged for other currencies, products, and services. As of February 2021, research produced by the University of Cambridge estimates that in 2017, there were 2.9 to 5.8 million unique users using a cryptocurrency wallet, most of them using bitcoin.

Bitcoin has been praised for its potential to disrupt traditional financial systems and for offering a greater degree of autonomy and privacy to users. However, it has also been criticized for its association with illegal activities and for its lack of regulation.

Bitcoin is highly volatile and the value of a bitcoin can fluctuate greatly in a short period of time. It has been known to experience significant price swings, and its value can be affected by a wide range of factors, including government regulations, investor sentiment, and global economic conditions.