Frequently asked questions about using Wikipedia's categories.
(This page is intended for readers of Wikipedia. Editors should see Wikipedia:FAQ/Categorization.)
What are categories?
Categories are groups of articles on similar topics.[note 1] At the bottom of an article, you will see a box containing the categories to which that article has been assigned. Simply click any of these categories to go to the corresponding category page. From there you can browse other articles on the same topic, or navigate through the category tree to find other related categories.
How are categories organized?
Most categories have a number of other categories listed as subcategories. These are listed in a special section of the category page, which appears above the list of articles belonging to the category. Click on these subcategories to navigate through the category tree to find more specific groups of articles.
Similarly, you may want to navigate in the other direction, to find more general groups of articles ("parent categories"). These are listed in the box at the bottom of a category page, just as on a Wikipedia article page.
Why is an article not in the categories I would expect?
Articles are not usually placed in every category to which they logically belong. In many cases they will not be placed directly into a category if they belong to one of its subcategories. This is because otherwise categories would become too large, and the list of categories on articles too long. To find the articles you are looking for, it may be necessary to dig down. For example, you won't find Oslo listed at the category called Cities, but if you start from there and click "Cities by country", and then "Cities and towns in Norway", you'll arrive at the right place. Conversely, if you are at the Oslo article and you want to find the category of all cities, start by clicking Cities and towns in Norway and navigate up the tree to its parent categories.
What types of categories are there?
The main types of categories used are:
- Administration categories or project categories – categories used mainly by Wikipedia's editors for project management purposes, rather than for browsing. Category:Wikipedia backlog links to many categories with articles that need to be worked on, sorted by reasons. Another common category is the stub category, which contains very short ("stub") articles that need expansion. Wikipedia:WikiProject Stub sorting/Stub types contains a giant list of stubs, sorted by topic.
- Container categories – categories that only contain other categories.
- Set categories – categories of articles on subjects in a particular class, such as Category:Villages in Poland.
- Topic categories – categories of articles relating to a particular topic, such as Category:Geography or Category:Paris.
- Set-and-topic categories – categories that are combinations of the two above types.
- Universal categories – categories used to provide a complete list of articles which are otherwise normally divided into subcategories.
Of course, categories are not the only Wikipedia feature for browsing articles on particular topics. Readers most often find related articles simply by clicking the links that appear in the article they are reading. To find which articles contain links to the article you are reading, click What links here at the left-hand side of the page. For a general starting point to browsing the encyclopedia, go to Portal:Contents. Wikipedia also has many pages containing lists, which serve a similar function to categories.
Can I specify categories when searching?
You can use the incategory search parameter to include only the pages in a particular category, or to exclude pages in a category as explained at Help:Searching. To find category names for use in the incategory search parameter, use Special:CategoryTree, or you can search for titles in the Category namespace. For example, .
But bare, simple search words or phrases will always find pages in a category even if no category is specified. This is because search terms match inside the category box (at the bottom of every page). These types of matches are automatically flagged parenthetically in the search results, saying "(Category category name)".
More FAQ topics
- Note: For simplicity the word "categories" is used here to refer to the categories that a reader sees at the bottom of a articles - not categories for pages other than articles (such as this page and talk pages).