Bitcoin is a digital asset and a payment system invented by Satoshi Nakamoto. Nakamoto introduced the idea on 31 October 2008 to a cryptography mailing list,[12] and released it as open-source software in 2009.[13] There have been several high profile claims to the identity of Satoshi Nakamoto; however, none of them have provided proof beyond doubt that back up their claims.[14]
The system is peer-to-peer and transactions take place between users directly, without an intermediary.[15]:4 These transactions are verified by network nodes and recorded in a public distributed ledger called the block chain, which uses bitcoin as its unit of account. Since the system works without a central repository or single administrator, the U.S. Treasury categorizes bitcoin as a decentralized virtual currency. Bitcoin is often called the first concurrency, although prior systems existed[note 5] and it is more correctly described as the first decentralized digital currency. Bitcoin is the largest of its kind in terms of total market value.
