From Organic Design wiki
A class is like a category but in a more structured sense. For example, the following Foo class has these related articles:
- Foo - the concepts of Foo. See Category:Classes.
- Portal:Foo - the primary entry point for all things Foo, does section zero query of members
- Template:Foo - articles transclude this template to designate it as a member of the Foo class
- Category:Foo - the template will automatically categorise the instances into here, but the portal is the primary entry point
- Create:Foo - default content which should be preloaded into newly created Foo instances
- Form:Foo - if a forms solutions is in use, then this will be the form for creating or editing Foo parameters