Hooks let you use different React features from your components. You can either use the built-in Hooks or combine them to build your own. This page lists all built-in Hooks in React. State lets a component “remember” information like user input.

There are 3 rules for hooks: Hooks can only be called inside React function components. Hooks can only be called at the top level of a component. Note: Hooks will not work in React class components. If you have stateful logic that needs to be reused in several components, you can build your own custom Hooks.

You must import Hooks from react. Here we are using the useState Hook to keep track of the application state. State generally refers to application data or properties that need to be tracked. There are 3 rules for hooks: Hooks can only be called inside React function components. Hooks can only be called at the top level of a component.

Hooks were a feature introduced years later in 2016 (in React's 16.8 version). Just to have an idea of what hooks are for and why are they improvement over what was done before, let's view an example of "pre-hooks" code against some modern React "post-hooks" code. In old React code, we used class components.