This is our top-level (or, mixing metaphors, "root") category.
Every other category should be a subcategory of one or more categories, provided that it covers no more subject-matter than the "parent" category.
Every article should be in at least one category; most can be good in two or more, eg a subject-matter category and a location category.
See Help:categorisation for more principles, and its "discussion" page for ideas and opinions about naming and relationships between categories.
This category has the following 6 subcategories, out of 6 total.