If ERC-20 was the Ethereum

token standard that launched a thousand ICOs, ERC-721 launched a thousand non-fungible tokens (NFTs). Originally the lesser-known cousin of the ERC-20, ERC-721 has grown to become a pillar of the Ethereum ecosystem, underpinning billions of dollars worth of NFTs.

Blockchains

are revolutionary because, for the first time, any type of value could be controlled by a computer program. Before the ERC-721 token standard, most tokens on blockchains functioned either as a currency, a store of value like gold, or a kind of stock or equity.

With ERC-721, it became easy to create tokens that were verifiably, cryptographically unique—and that could be linked to unique content, from artwork to music to sneakers.