Categories are used on your site to group similar content so that readers can easily find stories that interest them. Think of categories as being types of content that you will update regularly (similar to major sections or features in your publication).
You can add as many categories and subcategories to your site as you want, and links to these categories can easily be added to your navigation menu.
You can also easily add category widgets to any of the widget areas on your homepage or your non-homepage sidebar.
Learn more about adding, editing, and managing Categories here.