What is ABI?

ABI stands for Application Binary Interface. In the context of blockchain, especially Ethereum, it defines how to interact with smart contracts. It's an interface between two binary program modules, often between an operating system and user program. Specifically, it describes the methods and data structures of a smart contract in a way that allows external entities (like applications or other contracts) to call functions and receive data from the smart contract. The ABI specifies data types, function signatures, and how data should be encoded and decoded for transmission to and from the contract.