Calldata

Calldata refers to a temporary data storage location in a smart contract platform where data is sent along with a transaction when calling a function in a smart contract. Calldata is a non-persistent and read-only part of the transaction data, and once it is sent with a transaction, it cannot be modified by the smart contract.

The term is most commonly associated with Ethereum and the Ethereum Virtual Machine (EVM), and it is essential for interacting with smart contracts, as it carries all the necessary information (such as function arguments) to execute specific functions within the smart contract.

When a user or another contract calls a function of a smart contract, the parameters for that function are encoded and sent via the calldata field. The smart contract then decodes the calldata to retrieve the function parameters for processing.

Unlike contract storage (which is expensive in terms of gas fees), calldata is not stored on-chain after the transaction is processed. It is only used during the execution of the transaction and discarded afterward.

Calldata is more gas-efficient than other forms of storage on the blockchain, making it a preferable choice for passing large amounts of data when users don’t need to permanently store the data on-chain.