Ethereum has ERC standards to define strict compatibility requirements on smart contracts. ERC20 is the most popular one, but there are many others.

ERC standards and EIPs (Ethereum Improvement Proposals) have a number attached to them. For EIPs, the numbers mean a specific thing regarding the nature of the proposal

But what do the numbers (i.e. the 721 in ERC721) mean in ERC standards?

1 Answer 1


The EIP number is assigned by the associated EIP editor. (See here for a list of current editors.)

EIP-1 describes this responsibility in the following details:

Assign an EIP number (generally the PR number or, if preferred by the author, the Issue # if there was discussion in the Issues section of this repository about this EIP)

So, for example, ERC-721 derives its number from being issue #721 in the EIP repository.

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