Categories
Categories are used to organise the products in your store so your shoppers can find what they are looking for.
A product must have a primary category associated with it so you will need to add a category before you can add your first product. Products can also have secondary categories allowing them to be listed in more than one place. An example of this would be if you had a turkey in a "poultry" category, but also wanted to highlight it with your other Christmas products in a "Christmas" category.
Category structure
By setting the "parent category" you create a structure with top level categories and sub-categories underneath them. The number of levels is limitless, but typically this would be two or three. In deciding your categories consider the number of products within them. If there are too many split them into two or more sub-categories. Conversely if there is only one or two products in a category you might want to move them to another category with some more products.
The shop and category pages
The "/shop/" page lists all your top level categories. The "/c/" page is designed to list sub-categories or products and will therefore display both if you put products in a category that also has sub-categories. Category descriptions will appear at the beginning of the "/c/" page. If your category does not have an image associated with it your "no image" image will display on these pages instead.
Empty categories will auto-hide!
By design categories with no products will automatically be marked as "hidden" when a shopper visits it's page and therefore that category will no longer be displayed in your store front. To make it visible again go into the category in the control panel and uncheck the "hidden" box.
See also:
Controlling the order of lists
Images explained
Product overview