Bitcoin’s transaction history that serves as its public ledger and is stored by every node on the Bitcoin network. Transactions are stored in data groups called blocks. Blocks are arranged oldest to newest, and each block contains a hashed reference to the previous block, creating a chain that cannot easily be altered by an attacker.
Computers on the Bitcoin network verify and record transactions in the blockchain over time, and broadcast them to other computers. Every node on the Bitcoin network has their own copy of the blockchain.
See “How the Blockchain Works” for more information.