ERC-20 Tokens (Ethereum Blockchain)

ERC-20 is the interface standard that made tokens interchangeable on Ethereum. By agreeing on a handful of functions — transfer, approve, balanceOf and a few others — any wallet, exchange or contract can handle a token it has never seen before. That single convention is what allowed thousands of assets to launch without each one needing bespoke integration work.

It also has well-known sharp edges. The approve-and-transferFrom pattern means unlimited approvals left active on a contract remain exploitable indefinitely, which is how a large share of wallet drains actually happen. Tokens sent directly to a contract that does not implement recovery are permanently lost. And the standard says nothing about supply policy, mint permissions or transfer restrictions — a compliant ERC-20 can still be freely mintable or blacklist your address.

This section explains how the standard works and reviews specific ERC-20 projects, with attention to what the contract permits rather than what the whitepaper promises.