The components of a blockchain include nodes, blocks, and consensus mechanisms. Nodes are computers that maintain the blockchain's decentralized network, ensuring data integrity. Blocks store transaction data in a linked chain, with each block containing a cryptographic hash of the previous one, ensuring immutability. Consensus mechanisms like Proof of Work (PoW) or Proof of Stake (PoS) ensure agreement on transactions and maintain security across the blockchain network, preventing fraud or double-spending.