useRef is a Hook provided by React that allows you to create a mutable object that persists throughout the lifetime of a component. The object can be accessed and updated within the component, and changes to the object will not trigger a re-render of the component.

The useRef Hook returns a single value, which is a mutable ref object. This object has a current property that can be used to store any value, such as a DOM node or a variable.

One common use case for useRef is to reference a DOM element, which can be accessed and manipulated directly using the ref object's current property. For example, you could use useRef to store a reference to an input element and then call the focus() method on it in response to a user action.

Here's an example of using useRef to create a ref object and reference a DOM element:

import React, { useRef } from 'react';

function MyComponent() {
  const inputRef = useRef(null);

  function handleClick() {
    inputRef.current.focus();
  }

  return (
    <div>
      <input type="text" ref={inputRef} />
      <button onClick={handleClick}>Focus Input</button>
    </div>
  );
}

The useRef Hook is called to create a ref object inputRef with an initial value of null. The ref attribute is then passed to the input element, which assigns the reference to the current property of the ref object. Finally, a button is rendered with an onClick event handler that calls the focus() method on the ref object's current property, which will focus the input element.