When you are developing components, there is a basic, important question: how can you try them out? Of course, you could include them somewhere, in any page, but then whenever you want to see how they work, you must follow the full path through your application so that you can get to actually see the component.
Storybook is a UI development environment that lets you visualize your components in isolation, outside of your application, even making changes to them in an interactive way until you get them exactly right!
