A function selector is the first 4 bytes of the keccak256 hash of a Solidity function signature. It identifies which function to call in a smart contract.
For example, transfer(address,uint256) produces selector 0xa9059cbb.
How to use: Enter a 4-byte hex selector (e.g. 0xe45929eb) and press Search to find all known matching function signatures from the ABI Archive.