Definition: ERC-721

(Ethereum Request for Comments-721) A non-fungible token (NFT) standard on the Ethereum blockchain, which means each token certifies a unique object. Unlike ERC-20, which is the Ethereum standard for a digital currency token, each of which is the same as the other, ERC-721 is the smart contract standard for a unique entity in digital or physical form.

There Are Many ERC-721 Templates
ERC-721 is the standard format, but there are countless ways of programming an NFT smart contract, and various groups have developed their own templates. Although ERC-721 is limited in scope to NFTs, it is similar to a programming framework, such as for Windows or Android, whereby myriad applications can be developed within its boundaries. See ERC-20, Ethereum and NFT.

   MAJOR ERCs

    #     Token Type

   20     Fungible
   777    Fungible

   721    Non-fungible

   1155   Semi-fungible