React Hooks, introduced in version 16.8, enable the use of state and other React features in functional components without the need for class components, though they are not a complete replacement. This tutorial demonstrates how to handle state in both Hooks and class components, create custom Hooks, and automate tests using CircleCI. Class components offer lifecycle methods for state updates, while Hooks provide a simpler and more flexible approach with functions like useState and useEffect, which manage state and side effects. The tutorial guides the reader through creating a counter application using both approaches, writing tests with Jest and react-testing-library, and integrating these tests into a continuous integration pipeline with CircleCI. Although Hooks make code cleaner and easier to read, they can be challenging for beginners, and require additional Hooks to prevent unnecessary re-renders.