Bitcoin Block Header

A Bitcoin block header is a 80-byte data structure that serves as the unique identifier and metadata container for each block on the Bitcoin blockchain. It contains the block version, the hash of the previous block, the Merkle root of all transactions in the block, a timestamp, the difficulty target, and a nonce value used in the proof-of-work mining process. The block header is hashed twice using SHA-256 to produce the block hash, which becomes the previous block reference for the next block in the chain. This structure ensures immutability and allows nodes to verify the entire blockchain history efficiently. Example: During the Bitcoin halving event in May 2020, the block headers of newly mined blocks reflected the reduced mining reward of 6.25 BTC per block, and their timestamps and difficulty adjustments were recorded in the headers of blocks 630,000 and beyond. Why it matters for blockchain technology: Block headers are fundamental to blockchain security and efficiency, enabling nodes to validate the chain without storing complete block data. They create the cryptographic link between blocks that makes the blockchain immutable and resistant to tampering or reorganization attacks.

Category: blockchain technology

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