overlall its good, very very basic questions, oops, c# etc, as a Senior Softare Engineer,many times the component re-rendered without causing another render itself.is used when you want to trigger a re-render whenever the value changes. It's perfect for things that affect the UI.
useRef holds a mutable value that persists across renders without causing a re-render. It's great for storing things like DOM references, timers, or previous values.