For requesting browser API or sending/recv to server
Best done in a event handler
If it can’t be done in an event handler, then use useEffect()
useEffect( () => {}, [])
An example is commonly this is used in fetching user data after page load
The first parameter is the callback function
The second parameter is what to watch for changes
First Run Callback
Whenever you render the component for the first time, the useEffect callback function will be ran automatically. After the first render, it will run