Blockchain is a decentralized, distributed ledger technology that stores an immutable and permanent record of digital events or transactions. It works by recording and verifying data transactions on a shared digital ledger (blockchain) across multiple parties. Each node on the ledger is constantly communicating with all the other nodes to ensure that all versions of the ledger are up to date. Transactions are secured using cryptography, which ensures data integrity and immutability. The decentralization of the blockchain network makes it virtually impossible to alter the records.