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What is the genesis block?
The genesis block is the first block of a blockchain, written into the software rather than mined from an earlier block. Bitcoin's is dated January 3, 2009 and carries a newspaper headline from that day.
What it means for you
Every bitcoin transaction ever made traces back through the chain to this block, which is why nodes can check the whole history from a fixed starting point. Its 50-bitcoin reward can never be spent.
How it works
Bitcoin Core defines the genesis block in its own code: a timestamp of 1231006505 seconds, January 3, 2009, a reward of 50 BTC, and the text The Times 03/Jan/2009 Chancellor on brink of second bailout for banks, a headline from that day's London newspaper. The headline proves the block was not made before that date. Its hash, beginning with a long run of zeros, is hard-coded so every node starts from the same block. Because of how the code treats it, the coins in its first transaction cannot be spent.
Source: Bitcoin Core: chainparams.cpp (the genesis block) · checked 5 October 2026
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