Hooks are functions that let you “hook into” React state and lifecycle features from function components. Hooks don’t work inside classes — they let you use React without classes. (We don’t recommend rewriting your existing components overnight but you can start using Hooks in the new ones if you’d like.) React provides a few built-in Hooks like useState. You can also create your own Hooks to reuse stateful behavior between different components. We’ll look at the built-in Hooks first.