This category serves as a root for all other categories. It is our top-level category (looking at it another way, it is our root category).

Ideally, every other category should be a subcategory of at least one other, and every article should be in at least one category; many will fit well into two (e.g. location and subject-matter). A full list of existing categories can be found at Special:Categories.

To add a new category, just add [[Category:Categoryname]] to the article or existing category page (after checking whether any existing category is suitable).