In blockchain terms, the term genesis block refers to the first block in a blockchain. The creation of a genesis block marks the creation of a new blockchain. Subsequent blocks in the blockchain are modeled after the genesis block.
Unlike all other blocks on a blockchain, which must be mined, the genesis block is generated by the blockchain’s creator and is part of the blockchain’s source code. A block reward in the form of new coins is generated by the code when a genesis block is created, as with subsequent blocks.