Bitcoin is a software-based online payment system described by Satoshi Nakamoto in 2008 and introduced as open-source software in 2009. Payments 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 decentralised virtual currency. Media reports often refer to bitcoin as a cryptocurrency or digital currency.
Bitcoin is the first fully implemented decentralised cryptocurrency; most other cryptocurrencies are similar and derived from it. It is also the largest cryptocurrency in terms of total market value.Bitcoins are created as a reward for processing work in which users offer their computing power to verify and record payments into the public ledger. This activity is called mining, which individuals or companies engage in, in exchange for transaction fees and newly created bitcoins. Besides mining, bitcoins can be obtained in exchange for fiat money, products, and services. Users can send and receive bitcoin electronically for an optional transaction fee using wallet software on a personal computer, mobile device, a web application, or a specialised device called hardware wallet.
Bitcoin as a form of payment for products and services has grown, and merchants have an incentive to accept the digital currency because fees are lower than the 2–3% typically imposed by credit card processors. The European Banking Authority has warned that bitcoin lacks consumer protections. Unlike credit cards, any fees are paid by the purchaser, not the vendor. Bitcoin can be stolen, and chargebacks are impossible. As of July 2013, the commercial use of bitcoin was small compared to its use by speculators, which has contributed to price volatility.