To add a new category to a page you can click the Category button at the bottom of the page and type in the name you'd like your category to be called.
A full list of existing categories can be found at Special:Categories.
Pages in category "Browse"
“ This category may include pages and subcategories related to the active contributors to the...
“ This category lists stub articles on this wiki. A stub is a short article that can be expanded...
“ With the overwhelming popularity of this book, the Wikia Development Team has decided to give...