// GLOSSARY -- BLOCKCHAIN & CRYPTO FUNDAMENTALS

What is ERC-721?

1 min read Updated

ERC-721 is the standard for non-fungible tokens (NFTs) on Ethereum — defining an interface where each token has a unique ID and distinct ownership, enabling provable digital scarcity.

WHY IT MATTERS

ERC-721 formalized the concept of unique digital assets on blockchain. Unlike ERC-20 tokens (where each unit is identical), each ERC-721 token has a unique ID and can carry distinct metadata — images, attributes, provenance, and properties.

The standard defines ownership tracking, safe transfers, and metadata extensions. It powers the entire NFT ecosystem: digital art, collectibles, gaming items, domain names (ENS), and access credentials.

ERC-721's success demonstrated that blockchain can represent more than just fungible value — it can represent unique digital property with verifiable ownership and provenance.

FREQUENTLY ASKED QUESTIONS

How is ERC-721 different from ERC-20?
ERC-20 tokens are fungible (interchangeable). ERC-721 tokens are non-fungible — each has a unique ID and can represent distinct items. You can't swap one NFT for 'any other' the way you can with ERC-20 tokens.
What is token metadata?
Data associated with each NFT — typically a JSON file containing the name, description, image URL, and attributes. The metadata URI is stored on-chain; the actual data usually lives on IPFS or Arweave.
What about ERC-1155?
ERC-1155 is a multi-token standard supporting both fungible and non-fungible tokens in a single contract. More gas-efficient for collections, widely used in gaming.

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