ERC-20

ERC-20 is the Ethereum token standard for fungible tokens, meaning every unit is interchangeable with every other unit of the same token. It defines a small set of functions covering total supply, balance lookups, transfers, and the approve and transferFrom pattern that lets a smart contract spend tokens on a holder's behalf. That common interface is why one wallet can display thousands of different assets and why decentralised exchanges can list a new token quickly. Most stablecoins, governance tokens and exchange tokens on Ethereum are ERC-20 contracts, and many other EVM-compatible chains reuse the same design. The approval step carries real risk: an unlimited allowance granted to a malicious or compromised contract can be used to move your tokens later.