EIP-4337 Explained

ERC-4337 brought account abstraction to Ethereum without a consensus upgrade. Instead of adding a new transaction type, it introduces UserOperations — pseudo-transactions that smart wallets broadcast to a separate mempool and that bundlers submit through a central EntryPoint contract.

The EntryPoint contract is the single gatekeeper. It calls each wallet's validation hook, runs the requested execution, and handles gas accounting. Wallets deposit ETH into EntryPoint or rely on paymasters to cover fees on their behalf.

Because UserOperations are simulated before inclusion, bundlers avoid paying gas for operations that would revert. Aggregators batch signature verification across wallets for efficiency. The design keeps L1 consensus unchanged while opening a rich account layer on top.