ReasonJun

Delegatecall is a low-level Solidity opcode that allows a contract to execute code from another contract while using the state and storage of the calling contract. This can be used to implement a variety of features, such as: Upgrading contracts without losing data: Delegatecall can be used to upgrade a contract to a new version without losing any of the data stored in the contract. This is done..

Bytecode is a low-level language that the EVM interprets to execute functions. ABI (= Application Binary Interface) is a JSON file used in web apps to call smart contracts. Approximate structural differences between the existing Web 2.0 and Web 3.0: