Technical Definition

ERC-721

ERC-721 is an Ethereum token standard that defines a common interface for individually identifiable non-fungible tokens.

By Crypto University EditorialLast updated October 20, 2026

NFT (Non-Fungible Token)Token ContractContract Address (CA)

It helps users understand NFT token IDs, approvals, transfers, and marketplace compatibility.

A token name or image does not prove authenticity; verify the contract address.

Detailed Explanation

Each token is tracked by a token ID within a contract, allowing wallets and marketplaces to query ownership and transfer individual assets.

“One collection contract contains token ID 125, which identifies one distinct item in that collection.”

A token contract is a smart contract that defines and manages a token's balances, transfers, supply, and other programmable rules.

Permission you grant a smart contract to move a specific token from your wallet on your behalf.

A contract address is the blockchain address at which a smart contract, including many token contracts, is deployed.

A token that represents a unique item rather than an interchangeable unit of currency.

Minting creates new blockchain tokens according to the rules of the relevant smart contract or protocol.