Genesis Block

The genesis block is the very first block of a blockchain — block number zero, from which every subsequent block descends. Because each block contains a cryptographic reference to its predecessor, the genesis block is the anchor of the entire chain: every transaction ever recorded ultimately links back to it. Unlike later blocks, the genesis block is hardcoded into the blockchain's software rather than mined through normal operation.

Bitcoin's genesis block, created by Satoshi Nakamoto on January 3, 2009, is the most famous example. Nakamoto embedded a message in it: "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks" — a headline from that day's London Times, serving both as a timestamp proving the block was not created earlier and as a pointed commentary on the banking crisis Bitcoin was born into. The 50 BTC reward from that block is unspendable due to a quirk in how it was coded, and it has never moved.

A common misconception is that the genesis block holds special power over the network; it has no ongoing function beyond being the fixed starting point that all nodes agree on. Every blockchain has its own genesis block — Ethereum's, from July 2015, encoded the initial balances of participants in its crowdsale. The term has also entered crypto culture more broadly, with "genesis" used to label the founding edition of almost anything.