In React, refs are a way to reference a particular element in the DOM or a component instance created by React. Refs are useful when you need to access the DOM element or component instance to read or modify its properties or invoke its methods directly.

In class components, refs are typically created using the React.createRef() method and then attached to an element using the ref attribute. For example:

In functional components, refs can be created using the useRef hook, which returns a mutable ref object that can be updated during the component's lifetime. For example:

Using refs should be done with care as it can sometimes lead to code that is harder to understand and maintain. They should be used sparingly and only when necessary to access the DOM element or component instance.