https://itnext.io/react-custom-hooks-basics-f92de2a0ac0e

Photo by Chris Scott on UnsplashReact 16.8.0 introduces Hooks. Take notice that this is not React 17.0.0 because hooks can seamlessly integrate into your react code ,meaning they won’t break your existing code. React provides a bunch of hooks and you can read about them here in their amazing documentation.

Not only can you use the Hooks React provides, but you can also build your OWN hooks on top of them.