Help:Category

This article provides guidelines on creating and organizing categories.

When to use categories

Categories (along with other features like cross-references, lists, and infoboxes) help users find information, even if they don't know that it exists or what it's called.

Every page in the article namespace should belong to at least one category. Categories should be major topics that are likely to be useful to someone reading the article.

Article: The Serpent's Seed

Useful category: Category:Doctrines

Not useful: Category:Stuff fron Genesis

Questions to ask to determine whether it is appropriate to add an article to a category:

If the category does not already exist, is it possible to write a few paragraphs or more on the subject of the category, explaining it?
If you go to the article from the category, will it be obvious why the article was put in the category? Is the category subject prominently discussed in the article?

If the answer to either of these questions is no, then the category is probably inappropriate.

Guidelines

Some general guidelines

Categories are mainly used to browse through similar articles. Make decisions about the structure of categories and subcategories that make it easy for users to browse through similar articles.
An article will often be in several categories. Restraint should be used as categories become less effective the more there are on any given article.
Articles should not usually be in both a category and its subcategory. For example Golden Gate Bridge is in Category:Suspension bridges, so it should not also be in Category:Bridges. However there are occasions when this guideline can and should be ignored.
Check to see where siblings of the article reside. If there are few if any articles in a category, the article probably belongs in one of the subcategories.
Articles should be placed in categories with the same name. However, the article and the category do not have to be categorized the same way. The article can also be placed in categories populated with similar articles. The category can be put into categories populated with similar subcategories.
There are often occasions when articles might ideally be moved from a category to two or more of its subcategories, but not all of the subcategories exist. In such cases consider creating the additional subcategories, but if you decide not to do so, leave the articles in the parent category for the time being.
Bend the rules above when it makes sense, but only if no other solution can be found.
If you don't know where to put an article don't worry about it. Instead of adding a category, use the Template:Tl tag to bring attention to the article. Editors who love to categorize articles will find a good home for your article.

Categories vs. Lists vs. Info boxes

For alternative methods of grouping articles, and the circumstances in which they should be used, see BelieveTheSign:Categories, lists, and series boxes.

Categories do not form a tree

Each BelieveTheSign article can appear in more than one category, and each category can appear in more than one parent category. Multiple categorization schemes co-exist simultaneously. In other words, categories do not form a strict hierarchy or tree structure, but a more general directed acyclic graph (or close to it; see below).

Nevertheless, parts of the category graph will be tree-like, and it may be convenient to think of parts of the category graph as being like multiple overlapping trees. When applying the guidelines above, consider each tree to be independent of the overlapping trees. A person browsing through a hierarchy should find every article that belongs in that hierarchy. This can lead to a good deal of debate as to what the hierarchies actually are. To clarify the structure of the hierarchy and help people browse through it, you can add a classification to each category.

Cycles should usually be avoided

Although the MediaWiki software does not prevent loops, these usually should be avoided. Cycles can be confusing to some readers, they can challenge some automated searching processes and they can grow quite large.

How to put an article into categories

Adding an article to a category is as simple as editing the article and adding a link to the category. For instance, to add The Serpent's Seed article to the "Doctrines" category, you would edit the article and enter [[Category:Doctrines]] at the bottom of the article. The appeal of categories is that unlike lists, they update themselves automatically, and you don't have to edit the category to add an article to it. However, categories are not a substitute for lists, and you will find that many articles belong to both lists and categories.

When adding an article to a category, or creating categories, one should be careful to use the correct categories and subcategories. Horizontal categorization, directly below, refers to placing an article in the correct category while vertical categorization refers to placing an article in the correct subcategory.

How to create categories

Creating a category is as simple as adding a link to a category that doesn't yet exist. For instance, to create the "fluffy creatures" category, you would edit an article and enter [[Category:Fluffy creatures]] the same way as adding it to any other category. The Category:Doctrines will automatically be created when the edit is saved.

Category naming

Categories follow the same general naming conventions as articles, for example do not capitalise regular nouns. For specific conventions related to categories, see BelieveTheSign:Naming conventions (categories). Most categorizations are pretty straightforward, though.

Look before you leap

Before creating a category, look to see if one already exists. The best way to do this is to first add the category to your article but preview before saving. If the category appears in blue at the bottom of the page, the category already exists. If it is in red, then you will be creating a new category. Check the capitalization of the category name. For any red categories, you should look for categories with similar names before creating a new category. One way to do this is to think of the parent category for the new category. Search for it and then look at the subcategories in the parent. You may find that a category already exists that is similar to the one you are thinking about creating.

You may see some inconsistencies when first creating the category: it may alternate between appearing empty and appearing with your first additions. It will probably correct itself in a few minutes. Note that, although "uncreated" categories will correctly list articles that have been assigned to them, the category page itself does not exist until it is manually created. The easiest way to create the category page is to follow the red category link from your article and create a new category page with a parent category and a category description as explained in the next section.

How to create subcategories

Create subcategory pages by putting the name of the parent category on a category page that you would like to be the subcategory. Child categories (subcategories) are created by putting [[Category:parent_category_name]] on the lower-level category pages. For example, on a (sub)category page called category:Roses you put [[Category:Flowers]], Roses becomes a subcategory of Flowers.

Links to categories

You can create a link to a category page without adding the page to that category by using a colon before the word Category. Example: [[:Category:Automotive technologies]] appears as Category:Automotive technologies.

Redirected categories

Although it is possible to attempt to redirect categories by adding a line such as #REDIRECT [[:Category:Automotive technologies]] to a category, it is not generally recommended because of limitations in the mediawiki software. Categories "redirected" in this way do not prevent the addition of articles to the redirected category. Articles added to the "redirected" category do not show up as in the target category. Until these issues are addressed (in future versions of the software), #REDIRECT should not be added to category pages.

Category sorting

Contrary to some expectations, text after a pipe ("|") in a category link is not used in place of the category text. Rather, this text is used as the sort key on the category page itself. However, again contrary to expectations, that sort text is not displayed. One common application is to ignore "The" in article names, so [[Category:Rock and Roll Hall of Fame inductees|Beatles, The]] will make "The Beatles" list under B rather than T in the category.

Other specifics:

Don't start the category sort key with a lower case letter, unless you want to create a separate caption with that lower case letter in the category (note that the first lower case letter caption starts only after the last upper case letter caption)
Ordinals often have to be converted to Arabic numerals: e.g. Pope John IX: [[Category:Popes|John 09]] (+ zero added, there are XXIII popes with the name John)