End users interact with the search database in two distinct ways: They can type direct queries to search the database, or they can browse through the database contents using a set of categories you design. You assign resources in a search database to categories to clarify complexity. If a large number of items are in the database, it is helpful to group related items together. Your primary concern in setting up your categories should be usability so that end users can more quickly locate specific kinds of items.
The search server uses a hierarchy of categories called a taxonomy. The term taxonomy in general describes any system of categories. In the context of a networked resource database such as the search server database, it describes any method you choose of categorizing network resources to facilitate retrieval.