Block 0 or 1, used to describe the first block created and verified on a blockchain network.
A genesis block is the block that was first created on any blockchain network. Being the very first block, it has no reference to previous transactions or blocks on the blockchain. Thus, it is traditionally referred to as Block 1, although new blockchain networks have modified the title to Block 0. Whichever the case, this block serves as the fundamental model for every other block on the network.
A genesis block is different from every other block. For one, it does not refer to any previous block since it is the first ‘page’ on the digital ledger. Secondly, the reward attached to it is more than the reward attached to the others.