Blockchains are secure by design and are an example of a distributed computing system with high Byzantine fault tolerance. Decentralized consensus has therefore been achieved with a blockchain. This makes blockchains potentially suitable for the recording of events, medical records, and other records management activities, identity management, transaction processing, and documenting provenance.
The first blockchain was conceptualised by Satoshi Nakamoto in 2008 and implemented the following year as a core component of the digital currency bitcoin, where it serves as the public ledger for all transactions. The invention of the blockchain for bitcoin made it the first digital currency to solve the double spending problem, without the use of a trusted authority or central server. The bitcoin design has been the inspiration for other applications.
By 2007, a number of distributed systems for double-spending prevention had been proposed.
The cryptocurrency Bitcoin implemented a solution in early 2009. It uses a scheme called proof-of-work, to avoid the need for a trusted third party to timestamp transactions. These timestamps are recorded in its public ledger called the blockchain. This avoids anyone double-spending the currency.