In the absence of a central bank or a single administrator, Bitcoin is a decentralized digital currency that can be transferred from user to user without a middleman. Network nodes verify transactions with encryption before storing them in a blockchain, a public distributed ledger. The cryptocurrency was created by an unknown individual or group of individuals in 2008 under the pseudonym Satoshi Nakamoto. The currency was published as open-source software in 2009 and went into use.

Mining is the process by which bitcoins are generated. Bitcoins can be used to purchase goods and services. Due to its use in illegal transactions, the high amount of power (and hence carbon footprint) consumed by mining, price volatility, and thefts on exchanges, Bitcoin has been attacked. Several investors and economists have referred to it as a speculative bubble. Despite the fact that several regulatory organizations have issued warnings to investors, others have used bitcoin as an investment. El Salvador became the first government in the world to recognize Bitcoin as legal currency in September 2021.

The term "bitcoin" was defined in a white paper published on October 31, 2008. It is a combination of terms. Despite the lack of standard convention for referring to bitcoin, some publications refer to the technology and network as bitcoin, while others use bitcoin as the unit of account. The Wall Street Journal, The Chronicle of Higher Education, and the Oxford English Dictionary prefer a lowercase Bitcoin.