A blockchain is made up of several key components of a blockchain: blocks, nodes, consensus mechanisms, and cryptographic algorithms. Each block contains data such as transaction records, a timestamp, and a reference to the previous block (creating a chain). Nodes are the decentralized participants that validate and propagate blocks across the network. Consensus mechanisms (like Proof of Work or Proof of Stake) ensure agreement on transaction validity. Cryptography secures transactions and ensures data integrity. These components collectively ensure the security and functionality of blockchain systems.