Events

Events are the contract's public activity feed. They do not store business state directly, but they create logs that wallets, explorers, and analytics systems can read without replaying every line of contract code themselves.

Events are cheap compared with full storage writes, which makes them ideal for signaling what happened. Token standards like ERC-20 and ERC-721 rely heavily on events because external tools need a clean way to track transfers and approvals.

A useful beginner rule is this: if data must be enforced by the contract, keep it in storage. If data mainly helps off-chain systems understand execution, an event is often the better fit.