A type of database that operates as a decentralised, distributed, and self-proving digital ledger. It is used to record transactions chronologically and in a way that the record cannot be subsequently altered without the consensus of the network.

Self-proving means that by looking at a blockchain ledger, the user can tell whether the data in that blockchain is correct or whether it may have been tampered with. A blockchain therefore offers transparency and eliminates or reduces the need for intermediaries and physical documents where it is used.

Blockchain is best known as the technology behind digital currency Bitcoin. However, its uses in financial services, capital markets and other sectors are rapidly developing. For further details, see Practice note, Blockchain and smart contracts.