ERC-721 is a standard that defines a minimum interface—such as ownership details, security, and transfer methods—to create unique non-fungible tokens (NFTs) on the Ethereum blockchain. Unlike fungible tokens, which can be exchanged on a one-to-one basis, non-fungible tokens are unique and cannot be exchanged on a like-for-like basis. Each token has distinct characteristics or metadata that distinguish it from another, enabling it to represent ownership of unique assets such as digital art, collectibles, or real estate. The introduction of ERC-721 has paved the way for the explosion of digital ownership in various sectors, including art, gaming, and virtual real estate.