ERC-20
The standard interface for fungible tokens on Ethereum and EVM-compatible blockchains.
ERC-20 (Ethereum Request for Comments 20) is a technical standard defining a common set of functions that Ethereum-based tokens must implement: transfer, approve, allowance, balanceOf, totalSupply. Any token implementing ERC-20 is automatically compatible with wallets, DEXs, and DeFi protocols.
Before ERC-20, every token required custom integration. The standard — proposed by Fabian Vogelsteller in 2015 — enabled the ICO boom of 2017 and is the foundation of the EVM token ecosystem. Thousands of ERC-20 tokens exist, from major assets like USDC and LINK to long-tail project tokens.
ERC-20 tokens are fungible — each unit is identical and interchangeable. ERC-721 (NFTs) and ERC-1155 (multi-token) are later standards for non-fungible and semi-fungible assets respectively.