F2CRM provides unlimited configuration potential for creating categories and sub-categories in which to store/categorise your contact details.

F2CRM also provides a group management facility, allowing you to section your contacts off into groups, with a group generally referencing a particular website. That is, since F2CRM supports multi-site Joomla! registrations (via F2SignUp), all contacts who relate to a particular site can be grouped/sectioned off accordingly.  Note that a contact may exist within multiple groups.