Blockchain

A blockchain is a shared digital ledger that many computers maintain together. Transactions are grouped into batches called blocks, and each block is cryptographically linked to the one before it. This linking makes past records hard to alter, because changing one block would break its connection to every block that follows.

A blockchain is append-only, which means new records are added but existing ones are not edited or removed. The computers in the network follow a common set of rules to agree on which transactions are valid and in what order. This shared agreement lets the ledger operate without a single central authority holding the records.

Blockchains are the basis for cryptocurrencies and decentralized finance applications built on them. They carry risk, including software bugs in the code that runs on them and the loss of funds if the private keys that control an account are exposed or misplaced.