Wikipedia:FAQ/Categorization
These are frequently asked questions about the Wiipedia Category: feature.
What are categories?
See ...
What is the state of the feature?
The category feature appeared in the MediaWiki software v1.3, which was implemented on Wikipedia in late May 2004.
As of June 2004, category policies are still being determined through experimentation, discussion, and polls.
Known bugs
- Category pages still show old sub-categories and articles after edits.
- You need to make a dummy edit to the category page to fix this, e.g., add a space at the end of a line. Explain this in the edit summary (e.g. "Dummy edit to refresh"), and flag the edit as minor if you have a Wikipedia user account.
What is the purpose of categories?
Lists
- Categories allow articles to be grouped into a list,
- with the list page generated automatically,
- and a link from the article to the list page.
While an article may be in multiple lists, the goal is that browsing downwards from a list parent category, e.g. Category:Cities, should only arrive at articles that are cities, e.g. London, and not related articles e.g. List of famous London pubs.
There are some natural hierarchies of lists. One example is the scientific classification of organisms which would only place an article on one sub-category. Others ...
Currently the software does not allow you to look at and retrieve a list of all articles in sub-categories.
Related topics
To allow related articles to be grouped together, and those groupings placed into a hierarchy. For example, both London and List of famous London pubs could be in the category London.
There are some natural hierarchies of topics, e.g., placing Category:London history under Category:London and Category:English history.
Currently the software does not allow you to look at and retrieve a list of all articles in sub-categories.
Can pages be in more than one category?
Yes, this is expected.
What is the naming convention for categories?
Use the Wikipedia titling conventions of no unnecessary capital letters, i.e. use Category:Category examples instead of Category:Category Examples.
Lists
Use plurals, e.g. Category:Category Examples.
Topics
Editing
How do I place an article in categories?
Add the following to the article: [[Category:Category examples]]
How do I place a category in a parent categories?
In the same way as is done for articles, i.e. place the following in the category: [[Category:Examples]]
How do I reference a category on a page without categorising the page?
Put a colon at the front, e.g. [[:Category:Examples]].
Where should the category tag go in the article?
At the bottom of the article after the appendices. They are mostly placed before the inter-wiki language links, but some people prefer to place the category tags at the very bottom.
This ensures that when newcomers press "edit", they are immediately presented with the main article text, rather than the more esoteric links.
Somebody changed my categorization - what do I do?
All contributions to Wikipedia may be "edited mercilessly". If the change was not explained in the article history or talk page, try leaving a question on the relevant user's talk page. If you have a Wikipedia user account, they will respond on your talk page rather than their own.
I want to change the relationships of some categories - will anyone mind?
If you want to restructure some existing categories, it is best to discuss your plans with others working in the same areas.
What goes on a category page?
Please avoid repeating article contents and images. Category pages should be a fast cross-reference to articles and other categories.
Are "List ..." articles still needed?
There are many articles in Wikipedia called "List of ...", e.g. "List of assassins". They are still useful for showing "missing" articles.
Are topic and hierarchy templates still needed?
Many articles have side-boxes or footers linking to other articles and lists, sometimes using Wikipedia:Templates. While some of these are made redundant, others have useful grouping of the cross-references that cannot be done with categories.