Metatransaction

A metatransaction is a way of using a blockchain application without paying the network fee yourself. The user signs a message describing the action they want, such as transferring a token, and a third party called a relayer wraps that message in a real transaction, submits it and pays the gas fee. A smart contract then checks the user's signature and carries out the action as if the user had sent it. On Ethereum, metatransactions became popular from around 2018 so that new users could try apps without first buying ether, and they were standardised through proposals such as EIP-2771. The relayer may be paid by the app, in tokens or not at all. Many of these goals are now met through account abstraction and ERC-4337, where "paymasters" sponsor fees for smart-contract wallets.