Plain meaning
Start with the shortest useful explanation before going deeper.
A design pattern that replaces the rigid externally-owned account (EOA) model with programmable smart contract wallets capable of custom authentication, gas sponsorship, and batched transactions. ERC-4337 implements this on Ethereum via UserOperations, bundlers, an EntryPoint contract, and paymasters. EIP-7702 (Pectra upgrade, May 2025) extends this by allowing EOAs to delegate to smart contract logic.