Smart contract

A program deployed at an address on a blockchain that executes automatically when called by a transaction, according to its code. A contract exposes functions that read state (balances, configuration, permissions) and functions that write state (transfers, minting, burning, role changes, upgrades). Smart contracts implement tokens, decentralised exchanges, bridges and lending protocols. Their actions are recorded on-chain, but reconstructing a full call sequence may require execution traces or event logs. Many contracts reserve privileged write functions for administrator keys (see DeFi).