Library · Crypto, word by word · Tokens and supply
What is ERC-20?
ERC-20 is the common rulebook for fungible tokens on Ethereum, where every unit is identical, like dollars. It sets a shared list of functions—check a balance, send tokens, let another address spend them for you—so any wallet or exchange can handle any ERC-20 token the same way.
What it means for you
The approve function lets you give an app permission to move your tokens later, often for an unlimited amount, and that permission stays until you revoke it. Anyone can deploy an ERC-20 contract with any name or symbol, so the contract address, not the ticker, identifies the token you hold.
A common mistake: “Two tokens with the same name and ticker are the same token.”
In fact: Name and symbol are labels anyone can set when deploying a contract. Only the contract address identifies a token; a copy with the same ticker is a different asset.
How it works
An ERC-20 contract keeps a ledger of balances and exposes a fixed set of functions: totalSupply, balanceOf, transfer, transferFrom, approve and allowance, plus optional name, symbol and decimals. A Transfer event is emitted on every move, including zero-value transfers, and an Approval event on every approval; wallets and explorers read these events to show your history. Because name and symbol are optional labels the deployer chooses, the contract address is the real identity. Callers must handle a false return, since the standard allows a transfer to report failure.
Source: EIP-20: Token Standard · checked 4 October 2026
Often confused with
Related words
Educational content, not financial advice. Written by hand and checked against the source named above. Something wrong? Tell us and we reply within two business days.