Bitcoin is the world's first cryptocurrency, a form of electronic cash sent peer-to-peer without the need for a financial intermediary. It is the first decentralized digital currency: the system works without a central bank or single administrator. Bitcoins are sent from user to user on the peer-to-peer Bitcoin network directly, without the need for intermediaries. These transactions are verified by network nodes through cryptography and recorded in a public distributed ledger called a blockchain. Bitcoin was invented by an unknown person or group of people using the name Satoshi Nakamoto and released as open-source software in 2009.