What is Hook in React?

 A Hook lets you use state inside a function component.

Before Hooks, only class components could store state.
Now we use useState.


Simple Counter Example


import React, { useState } from "react";

function Counter() {

  const [number, setNumber] = useState(0);

  return (
    <div>
      <h2>Counter: {number}</h2>

      <button onClick={() => setNumber(number + 1)}>
        Increase
      </button>
    </div>
  );
}

export default Counter;


When button is clicked:

  • setNumber(number + 1) runs

  • React updates state

  • Component re-renders automatically

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