Hooks :

Hooks are JavaScript functions, but they impose additional rules:

• Hooks must be named with a use prefix (i.e. useFishingPole)
• Only call Hooks at the top level. Don’t call Hooks inside loops, conditions, or nested functions.
• Only call Hooks from React function components. Don’t call Hooks from regular JavaScript functions. (There is just one - - - other valid place to call Hooks — your own custom Hooks. We’ll learn about them in a moment.

• Built In Hooks useState() Returns a stateVariable and setterFunction for you to use to manage state in a functional component

In this example …

clicks is the state variable, which will store the number of clicks setClicks is a function that is called to change the value of clicks