Timestamp: The time at which the block was mined

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Bits (Difficulty Target): A packed representation of the target difficulty that the block's hash must be less than or equal to. This adjusts roughly every two weeks to maintain a consistent block mining time.
Nonce: A 32-bit number that miners repeatedly change to find a block hash that meets the difficulty target. Finding this "nonce" is the "Proof of Work."
Transactions:

Beneath the block header, the diagram canadian biotechnology email list shows a list of verified transactions.
The first transaction in every block is a special coinbase transaction. This is how the miner who successfully found the block collects the block reward (newly minted Bitcoin) and all the transaction fees from the other transactions included in that block.
Subsequent transactions represent the transfers of Bitcoin between users.
Block Hash:

The unique cryptographic hash of the current block's header. This is the identifier for the block and becomes the "Previous Block Hash" for the next block in the chain.
The "Chain" and Decentralization
Beyond individual blocks, a diagram also visually conveys:

Sequential Linking: Multiple blocks are shown connected chronologically. An arrow typically points from Block X to Block X+1, emphasizing that Block X+1 contains the hash of Block X, forming an unbroken, linear sequence.