EIP-4337 presents a novel concept called a UserOperation, which is essentially a detailed description of a user's intended transaction. These UserOperations are collected in an alternative holding area, much like a pre-confirmation queue, known as an ***"alt mempool."***
In the Ethereum network ecosystem, there are specialized nodes referred to as "bundlers." These bundlers gather UserOperations from the alt mempool and compile them into a single, comprehensive transaction, aptly named a "bundle transaction."
The bundle transaction is then directed to a unique and centralized smart contract on the blockchain, the "EntryPoint." As the only EntryPoint contract in existence, it plays a pivotal role in this process. Bundlers invoke a function on the EntryPoint called **`handleOps`**.
The ***`handleOps`*** function is responsible for taking in the bundle transaction and coordinating with each involved account's smart contract wallet to execute the **`validateUserOp`** function. This critical function checks the legitimacy of the operation's signature and approves the transaction fee if the operation is deemed valid, setting the stage for the operation's execution.
To actually carry out the intended action, each smart contract wallet is required to have another function in place, typically expected to be named ***`"execute".`***This function is what puts the UserOperation into action, once given the go-ahead by the EntryPoint contract.
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