Categories are pre-defined searches. They differ from "Saved Searches" in that, categories automatically execute a saved search with pre-defined values.
Categories appear under the "Categories" Tab.
To create a category, perform the following:
When a user clicks on the category entry, the search parameters you specified will be used to fire a new search.
This helps users get search results for complicated search queries without having to specify the search parameters. Users of the categories do not see the search parameters, all they see is the results of the search.
It is perfectly normal to see different search results for the same category because new documents may have been created that fit the pre-defined search parameters or similarly, document that fit the search criteria previously may have been altered or deleted.
Creating a Category is subject to security rights. Only the System Administrator, members of the "Administrators" system user group and the Category & Search Administrator designees can create categories.