Blockchain is a technology that allows for the secure and transparent recording of data in a decentralized manner. It was originally introduced as the underlying technology behind cryptocurrencies like Bitcoin but has since found applications in various industries beyond finance.

At its core, a blockchain is a distributed and immutable ledger or database that is maintained by a network of computers, known as nodes. Each node in the network contains a copy of the entire blockchain, and all nodes work together to validate and record new transactions or data entries.