A category is basically just a page for your site. It will appear in the Menu, and you can add other pages to it. Common categories are Home, About Us, Products, Services, Testimonials and Contact Us. Of course, you can add others. There are three options under the 'Add Category' button - FreeStyle which is used for adding a single category - Menu Divider used to separate items on your menu with a line or a space - and Newsletter where you can place lots of pages for creating your own newsletter. Click below for more information.