Bitcoin is an electronic currency created in 2009 by Satoshi Nakamoto. The name is also associated with the open source software he designed, and also uses a peer-to-peer network without centralized storage or a single administrator where the US Department of the Treasury calls bitcoin a decentralized currency. Unlike currencies in general, bitcoin does not depend on trusting the main issuer. Bitcoin uses a distributed database and spreads to nodes of a P2P network to transaction journals, and uses cryptography to provide basic security functions, such as ensuring that bitcoins can only be spent by their rightful owner, and should never be done more than once.