Genesis block is the first block created for a particular blockchain network. It does not reference a normal previous block and serves as the starting point for the chain.

The genesis block is normally defined by the protocol or its initial software configuration. Its contents and identifier help nodes determine that they are operating on the intended network.

Why the genesis block matters

Every regular block references an earlier block. The genesis block provides the initial point from which this sequence begins. It therefore forms part of the basic identity of a blockchain.

Changing the genesis block generally means creating a different chain or incompatible network history rather than simply modifying an existing block.