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ABI (Application Binary Interface)
A standardized description of a smart contract's functions and data structures, letting external applications know how to correctly interact with it.
An ABI (Application Binary Interface) is a standardized description of a smart contract's available functions, their expected inputs and outputs, and its data structures, letting external applications (wallets, other contracts, front-end interfaces) know exactly how to correctly format a call to that contract.
Without a contract's ABI, an application would have no reliable way to know what functions a deployed contract's raw bytecode (see Kaavon's "Bytecode" glossary definition) actually exposes or how to correctly call them.
Examples
- A wallet application needs a smart contract's ABI to display and correctly format an interaction with that contract's functions.
- A contract's ABI describes its interface — what functions exist and what they expect — not the contract's actual internal logic.