A catalog represents a collection of products that you group into categories. You can then use this information to create, within a Commerce Server-enabled Web site, Web pages that let your customers browse your collection of products.
The categories in your catalogs can have sub-categories, and products may appear in multiple categories. You can define a product with variations, for example, the same shirt can have different colors. These are called aproduct variants. You can also create catalogs that display on your Web site in different languages and different currencies.
You can link two products together, so that when one is viewed, the other appears somewhere on your Web site page as an alternate suggestion. You can export your catalogs to XML, which is a textual format that is computer-friendly and can be consumed easily by technological partners. You can also import catalogs in XML format.