Definition

What is Modifier?

A modifier is a reusable Solidity construct that wraps a function with pre- or post-conditions, such as checking that the caller is the owner before the body runs.

Modifiers keep permission and validation logic in one place. onlyOwner, nonReentrant, and whenNotPaused are the ones you see most.

Definition by Adwait Keshari, founder of Monsmith.