Bitcoin is a peer-to-peer payment system introduced as open source software in 2009 by developer Satoshi Nakamoto. The digital currency created and used in the system is alternatively referred to as a virtual currency, electronic money, or a cryptocurrency because cryptography is used to control its creation and transfer.[4] Conventionally, the capitalized word "Bitcoin" refers to the technology and network, whereas lowercase "bitcoin" refers to the digital currency.[5] The Bitcoin system is not controlled by a single entity, like a central bank, which has led the US Treasury to call bitcoin a decentralized currency,[6] although it does not meet the generally recognized definition of a currency.
