Bitcoin is a distributed, peer-to-peer digital currency that functions without the intermediation of any central authority.The concept was introduced in a 2008 paper by a pseudonymous developer known as "Satoshi Nakamoto".
Bitcoin has been called a cryptocurrency because it is decentralized and uses cryptography to control transactions and prevent double-spending, a problem for digital currencies.[8] Once validated, every individual transaction is permanently recorded in a public ledger known as the blockchain.


Bitcoins are stored by associating them with addresses called "wallets". Wallets can be stored on web services, on local hardware like PCs and mobile devices, or on paper print-outs. Thefts of Bitcoins from web services and online wallets have been covered in the media, prompting assertions that the safest way to store Bitcoins is on secure paper wallets.