Definition

What is Event?

An event is a log entry a contract emits during execution; it is cheap to write, cannot be read by contracts, and is how off-chain applications learn what happened.

Indexers, wallets, and explorers subscribe to events such as Transfer to build history without replaying every transaction. Emitting a well-designed event for every state change is part of writing a contract others can build on.

Definition by Adwait Keshari, founder of Monsmith.