ERC-721: Non-Fungible Token Standard
NFTs, digital ownership, gaming assets, and on-chain certificates all use ERC-721. The standard that launched the NFT market.
What It Defines
Defines the interface for non-fungible tokens (NFTs): unique token IDs, ownerOf, safeTransferFrom, approve, getApproved, tokenURI for metadata. Each token is distinct and not interchangeable.
Canonical (Normative)
Convenient (Practical)
The Ethereum community's open process for proposing changes to the protocol. EIPs cover core protocol changes; ERCs (Ethereum Request for Comments) cover application-layer standards like token interfaces.
Related Specs
ERC-20 is the most widely deployed standard in the Ethereum ecosystem. Every DeFi integration, exchange, and wallet interacts with ERC-20 tokens constantly.
More gas-efficient than deploying separate ERC-20 + ERC-721 contracts. Standard for gaming, semi-fungible assets, and multi-edition NFTs.
Every NFT's display (image, name, description, traits) is driven by this metadata schema. Off-chain storage of this JSON (IPFS, Arweave, HTTP) is a critical design decision.