The composition of the block header is an intricate and highly consequential process. If Bitcoin is a living, breathing organism, then the block header is the heart of the entire machine. The “block” in the Bitcoin blockchain is what moves and settles millions of dollars of value every 10 minutes and in the block. The block header is what notarizes the funds in a block, votes on consensus decisions and ultimately directs and defines the movement and legitimacy of Bitcoin transactions.
The version number provides means for network softfork upgrades. The previous block hash links the current block to its parent, creating the chain in “blockchain”. The Merkle root cryptographically ties all the transactions in a block to their associated header. The timestamp acts as a verifiable timestamping system, which is useful in many applications outside of Bitcoin. The encoded target difficulty lets the miner know what the network will accept as valid. And finally, the nonce provides a dedicated search space for the miners to mine, propelling the network forward.
This post aims to provide a technical overview of each of these fields with the intention of being a technical reference for the Bitcoin block header. Read more
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