Outlook

Category structure in Wikimedia Commons

Principles

Shortcut

• COM:CATPRI

The main principles are:

Hierarchic principle

The category structure is (ideally) a multi-hierarchy with a single root category, Category:CommonsRoot. All categories (except CommonsRoot) should be contained in at least one other category. There should be no cycles (i.e. a category should not contain itself, directly or indirectly).

Modularity principle

The page (file, category) should be put in the most specific category/categories that fit(s) the page (not directly to its parent categories). A category can have more parent categories. A category can combine two (or more) different criteria; such categories are called "compound categories" or "intersection categories". E.g. the root category Category:Churches and the root category Category:Russia have a common subcategory Churches in Russia.