Hooks

Summary

Functions (`useState`, `useEffect`, `useContext`, etc.) that let function components use state, side effects and other React features — the foundation of modern React.

• 1Learn the 'Rules of Hooks' — only call at the top level, only from React functions.
• 2Work through `useState`, `useEffect` and `useRef` one at a time with small examples.
• 3Practice `useEffect`'s dependency array and cleanup function.