Help:Categorization
- For more detailed guidelines on creating and organizing categories, see Wikipedia:Help:Category. More technical information can be found at Wikipedia:Categorization.
Categories allow articles to be placed in one or more groups, and allow those groups to be further categorized. When an article belongs to a category, it will contain a special link to a page that describes the category. Similarly, when a sub-category belongs to a parent category, it will contain a special link to the parent category's page.
Each category page contains an introduction that can be edited like an article, and an automatically generated list of links to sub-categories and articles that belong to the category. Categories do not form a strict hierarchy or tree of categories, since each article can appear in more than one category, and each category can appear in more than one parent category. This allows multiple categorization schemes to co-exist simultaneously. It is possible to construct loops in the category space, but this is discouraged.
It is expected that most pages will be members of more than one category. Similarly, each category can be a member of more than one parent category.
Contents
Categories vs. Lists
Grouping articles into a category is not the same as making a list of articles. To make a list of articles, you edit the list directly; but to place articles into a category, you edit each article and insert a category tag by placing [[Category:category_name]] in the body of the text. This automatically adds those articles as a list on the category's page. Despite the difference in how they are maintained, it is sometimes convenient to think of a category as a list of articles. While an article may be in multiple lists, the goal is that browsing downwards from a list parent category, e.g. Category:People, should only arrive at articles that are about people, e.g. John Lennon, and not related articles e.g. 251 Menlove Avenue.
- Further information on this topic can be found at Wikipedia:Categories, lists, and navigation templates.
Maintenance Categories
Some categories exist to aid maintenance of the UniWiki, for example, template categories and redirect categories. Maintenance categories are often added by templates,
| {{...}} |
rather than by the "wikilink" structure,
| [[...]] |
. Benefits of template usage include the ability to populate more than one category with a single template, inclusion of text to explain the rationale of a given categorization(s), the ability to readily include/exclude certain pages or types of pages, and so on. Contributors may monitor these maintenance categories for many reasons to include compliance with policies and guidelines that pertain to various conventions, such as page naming conventions.
Naming convention for Categories
Use the UniWiki titling conventions of no unnecessary capital letters or abbreviations, i.e. use [[Category:Category examples]] instead of [[Category:Category E.g.]]. Avoid ambiguities.
Lists
If the category collects articles, then avoid the word List in the name of the category, and use plurals, e.g. Category:Popes.
However, if the category collects lists, then using the word Lists in the name of the category is appropriate, e.g. Category:Lists of radio stations.
Topics
Use the topic name without indicating structure, e.g. [[Category:History of London]] instead of [[Category:History - Europe - UK - London]].
Editing articles
- See also: MediaWiki User's Guide: Using Categories.
Adding an article to a category
To add an article to a category, edit the article and add [[Category:Surname]] at the bottom of the article.
- For example: [[Category:Mind-body interventions]].
Linking to a category without categorizing
To link to the category page, put a colon before the word "category", inside the link, e.g.
[[:Category:United States]], which will appear as Category:United States.
Category tag location
Category tags should be placed at the bottom of the article, after the appendices (e.g. References and External links) and before any inter-wiki language links and stub templates (see UMoS:Layout). This ensures that when newcomers press "edit", they are immediately presented with the main article text, rather than the more esoteric category tags. It also ensures that the category tags are in a consistent place so they are easy to find when an editor is updating the categorization of a bunch of articles.
Maintaining categories
Restructuring categories
If you want to restructure existing categories, it is best to discuss your plans with others working in the same areas, or at least to announce your intentions. This is to avoid the situation where someone is placing an article into multiple categories, someone else is populating a category with multiple articles and parent categories, while someone else is trying to restructure part of the category tree, and nobody ends up with what they want.
Category page contents
Category pages exist to be a convenient cross-reference to related articles and other categories.
A category page should contain a brief description of the purpose of the category.
A prominent link to the most important article in the category is usually a good idea, but please avoid copying large quantities of text or images from an article to a category page. If a category and a page have a one-to-one correspondence, then the template {{main}} or similar is often the best solution. Introductions should be short and only navigation templates that facilitate moving between categories or category pages can be included.
Categories which have a main article
Take John Lennon and Category:John Lennon or The KLF and Category:The KLF. Should all category memberships which relate to Lennon or the KLF (but not to, for example, the state of the article) be added to Category:John Lennon/The KLF and removed from the article? That would seem to follow from literal interpretation of the "no categorizing into a subcategory and category at once" rule, but it forces readers to click an extra time and hides relationships from them.
The article should be left in those categories it would belong to if it had no category of its own; see Wikipedia:Categorization and subcategories#Topic article rule as well as Wikipedia:Categorization#Some general guidelines.
State of the Category feature
The category feature appeared in the MediaWiki software v1.3, which was implemented on Wikipedia in late May 2004.
Initially categories were displayed at the top right of articles, but they were soon moved to the bottom due to layout conflicts. (Not every skin has them at the bottom; e.g. Cologne Blue has them at top right.)
Known issues
Reported categorisation bugs can be seen at Phabricator. See also: Wikipedia:Categorization#Known category-related bugs.
- Work-around: 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.
- Categories can be sub-categories of themselves [3].
- Work-around: Don't do it.
- Categories cannot be redirected [4].
- Work-around: Don't do it, place a link on the page instead if it already exists.
- Layout issues:
- Work-around: Edit category pages so that there is only one category tag per line.
How do I report bugs?
Bugs should be reported to the Wikimedia Phabricator website. (See Wikipedia:Bug reports and feature requests for instructions.)
How do I request feature enhancements?
Enhancements can be requested at the Phabricator website. (See also mw:MediaWiki roadmap.)
What is the state of categorization?
When trying to categorize an article, it may be difficult to tell into which categories it should be placed. Sometimes when trying to categorize by a field of interest, one intersects with someone else's efforts from another field.
Category policies are still being refined by experimentation, discussion, and polls. Categorizations and systems are likely to be discussed and improved upon for a very long time. To be part of the discussion see Wikipedia talk:Categorization.
Related topics
To allow related articles to be grouped together, and those groupings placed into a hierarchy. For example, both Gwalior and History of Gwalior could be in the Category : Gwalior.
There are some natural hierarchies of topics, e.g., placing Category:History of India under Category:Asia and Category:History.
Topic categories are unlikely to be subcategories of list categories.
Currently the software does not allow you to look at Category:People and retrieve a list of all articles in sub-categories.
Why might a category list not be up to date?
Sometimes, pages are not placed in categories manually by Wikipedia editors, but by means of templates, which can be used to place identical information (including category membership information) on many different pages at once. When the information on such a template is edited, the pages containing that template are updated, but not necessarily updated immediately. This means that pages might not always appear in the most current categories. However, this problem usually affects project maintenance categories rather than the categories used for browsing.
Various other temporary delays may sometimes mean that lists of category members or subcategories, or the page counts given, are not completely up to date. So if you are editing Wikipedia and find that your page hasn't yet shown up in a category or been removed from an old category, don't panic! The problem may resolve itself within minutes, but sometimes it may take longer, in some cases days, even weeks. (It may help if you make a null edit to the page.)
Tools
There are some tools which help in maintaining and analysing categories. These include:
- CatCycle, to trace cycles in the category structure, or find the relationship between two categories
- CatScan v3.0, a flexible tool to scan categories, selecting pages on many categories
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