Product Catalog Listing
The products in your catalog can be listed in more then few ways. The most common is when user click on a category, then all products that belong to this category will be listed with the short description and thumbnail image.    Other 2 options are as grid (left to right as image and name) or "Multi-Buy" that allow user to check number of items on page and add them all to cart in one click.
       
The user can tag his browser to not display the images in the listing for faster loading. He also can jump to listing by the product company, sale products, new products or use the index in the bottom to display all items that starts with a certain character.    He can also jump to next, previews, first or last page if available.    From this listing he can add this product to the cart or link to the full description page that also display any option if available, full image, related products and users reviews.   
If products was set to have title and Format as well, the title is the link to the full description and the name is link to all products with the same name (If it's a music store, name will be the artist, title will be the album and format can be CD, Cassette, DVD, VHS, Etc...)    
 
You can add as many categories you wish and as many levels and sub categories down. You can also assign multiple parent categories so one category can be display on many parent categories. Just beware of duplicate content as search engines do not like it...