A hook is a special function that helps us to access usefull react features. For Example useState is a hook that helps to add react state to function components.
If you have wrote some code in a function component and you realise that the you need to add some state to it, then you can use a hook inside the function component (previosuly it was achieved by changing it to a class).
It first declares our variable as a state variable. Normally variables disappear when the function exits but the state variables are preserved by React.
The argument that we pass in useState is the initial state of the hook!
const [count, setCount] = useState(0);
In order to update the current count, we can call the setCount().
setCount(count + 1)
React will remember the current value between re-renders and provide the most recent one to our function.
In this Example, we just want how many times the user clicked the "Click Me" Button, so the setCount(count + 1) is used whenever the the button is clicked, thereby react preserves state variables between re renders and update the count value!!!