A stub is a short article which is not complete yet. See it as an invitiation to anyone who finds it to expand and improve this article. To mark an article as a stub include the stub template at the bottom of the page with the following command:
All articles marked as stubs will automatically be included in Category:Stubs.
Note that there is only one stub category in the CFD-Wiki. Wikipedia has many stub categories, but since the CFD-Wiki is a fairly small and focused Wiki there is no need for more than one stub category here.