Wiki Categories are purely conceptual groupings for organizing the contents of a Wiki. To include a page on a special category, just link to the category page from the bottom of the page.
%%category [CategoryPage]%%The %%category command turns an ordinary wikipage link into a pop-up screen which lists all pages referring to the [CategoryPage]. When you click the link, the referenced by information of the category page is retrieved from the server.
See also %%category [BrushedTemplate] and [JSPWikiPlugins]%%