The Bitcoin protocol for the bitcoin cryptocurrency is an open source cryptographic protocol that operates on a peer-to-peer network. It uses a chain or "blockchain" of transactions to achieve consensus and to solve the double-spending problem. The blockchain is distributed internationally using peer-to-peer filesharing technology similar to BitTorrent. It was designed in 2008 and released in 2009 by "Satoshi Nakamoto", the pseudonym of the original developer or group of developers.