Help:Categorization

The following are guidelines that you are welcome to edit. However, if you'd like to ask questions, make suggestions, or discuss categorization ideas, please click the Discussion tab above.

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 article should belong to at least one category. The categories to be included, which serve as classifications, should be the significant (useful) topics to which the subject of the article most closely belongs to as a member, and where users are most likely to look if they can't remember the name of the thing they are trying to look up. For example:


 * Article: United States Vital Records
 * Useful category: Category:United States of America
 * Not as useful: Category:United States of America records which start with V

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?
 * Does the category fit into the overall category system? Categories that don't fit are often deleted.

If the answer to any of these questions is no, then the category is probably inappropriate. Note that it is always appropriate to add articles to categories that fit into well established taxonomies, such as those within the Library of Congress Authorities.

Some general guidelines

 * 1) Categories are often 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.
 * 2) 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.
 * 3) Usually, articles should not be in both a category and its subcategory. For example, Alaska Cemeteries is in Category:Alaska, so it should not also be in Category:United States of America . However, there are occasions when this guideline can and should be ignored.
 * 4) If an article is placed in a category with the same name, 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. For an example of this see Wikipedia's George W. Bush and Category:George W. Bush.3
 * 5) 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.
 * 6) Categories appear without annotations, so be careful of neutral point of view when creating or filling categories. Categories that are not self-evident, or are shown through reliable sources to be controversial, should not be included on the article.
 * 7) An article should normally possess all the referenced information necessary to demonstrate that it belongs in each of its categories. Avoid including categories in an article if the article itself doesn't adequately show it belongs there.4
 * 8) If you don't know where to put an article, don't worry about it. Editors who love to categorize articles will find a good home for your article.
 * 9) Bend the rules above when it makes sense, especially when it is the best solution that can be found under the circumstances.

Categories do not form a tree


Each Wikipedia 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.6

Cycles should usually be avoided
Although the MediaWiki software does not prevent ^cycles (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.

However, acceptable loops also exist. Self-referencing systems such as the meta- fields naturally create cycles that provide many examples. This type of cycle involves making a category one of its own subcategories. A real-world example of a self-referencing system is “education about education,” such as:


 * Classification: Education: Social sciences: Academic disciplines: Academia: Education: ...

Another type of cycle involves making two categories subcategories of each other. Loops such as these can be avoided by linking the categories manually to each other by adding a See also: reference to each category page. For an example of this on Wikipedia, see Category:World Trade Center and Category:September 11, 2001 attacks.

= How to categorize an article =

Searching for an existing category
Before creating a category, look to see if a suitable one already exists. The best way to do this is to first add the category to your article but preview before saving. When previewing a page, scroll to the bottom of the browser window to see the categories. If the category appears in blue, the category already exists. If it is in red, then you will be creating a new category. Before saving the document and thus creating the new category, you should look for categories with similar names in case one will suffice for your needs. One way to do this is to think of possible names for the parent category of the category you're about to create. Search for this parent category 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.

If a search fails to produce categories that are close to what you want, you may want to browse the existing categories like so:


 * 1) Go to the "Special pages" link in the Toolbox on the left side of the screen and click on the link.
 * 2) Select "Categories" from the "Special pages for all users" list.
 * 3) Select the needed category from the Categories page.
 * 4) Copy the category name to ensure accurate use. (Highlight the name, then press Ctrl-C.)

Adding the category to the article

 * 1) Click the edit tab of the article you will categorize.
 * 2) Go to the bottom of the page.
 * 3) Paste the category title into the page.
 * 4) Add two square brackets before and after the category text. For example, if you want to add the category "United States" to an article, type    at the bottom of the article.
 * 5) Multiple categories can be added. Separate each bracketed entry with a space. For example, if you wanted to categorize a page under "United States" and "Indians of North America," the entry you would add to the page would look like this:    
 * 6) In the Summary field in the edit screen, add the text "cat." This will allow others viewing the History of the article to quickly see that the change you made to the page was to add a category.
 * 7) Click Save Page.

Finding intuitive terms for a category title
If the category you want does not exist, you can create it. Naming a category well can be tricky. Terms that are intuitive to you won't necessarily be intuitive to other users. The most efficient way to arrive at a good name for a category is to first obtain a list of terms that others have used for the topic in question. Such a list of terms is available in a library catalog. Librarians have been categorizing knowledge for generations, so it's smart to leverage their experience.

Since this wiki is in English and is somewhat associated with the collection of the Family History Library in Salt Lake City, Utah, United States, we tend to rely on two library catalogs for finding category terms. The first is the Library of Congress Authorities. The second is the Family History Library Catalog (Subject Search).

Naming conventions can be extremely helpful in creating a title you won't have to fix later. For some very helpful guidelines, see Wikipedia:Naming Conventions.

Caution: academic vs. popular terms
Although library catalogs can be a useful source of category terms, remember that catalogs are created by mere mortals. Even cataloging experts make mistakes. Perhaps the most common mistake is the use of terms preferred by academics rather than regular users. When faced with a choice between academic and popular terms, remember the nature of our audience. Most are regular people -- not academics, and not necessarily even genealogists. Since the purpose of categories is to make the content more findable by the audience, and since the audience is Joe Public, those of us who create category names should choose popular, non-academic terms.

To add the category to the page, follow the instructions above titled "Adding the category to the article."

= Fixing categories =

Philosophy
If you feel someone else categorized an article in error, it is best to discuss the matter with them before disassociating the article and the category. Use the article's Discussion page to do this.

Steps
Disassociating a category from an article is as easy as pressing the delete or backspace key. Follow these steps to remove a category from an article:


 * 1) Find the article that needs editing.
 * 2) Select the Edit tab.
 * 3) Move the cursor to the bottom of the article.
 * 4) Delete the category name using either backspace or delete key.
 * 5) Save the article.

Redirecting categories
Although it is possible to attempt to redirect categories by adding a line such as  #REDIRECT Category:United States  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.

= Subcategories =

Should I use subcategories?
We plan to adopt the Wikipedia model, which is to create overlapping taxonomies of categories and subcategories that make it easier for customers to browse related articles. To see some well-constructed tips on when subcategorization is useful and not useful, see Wikipedia:Categorization and Subcategories.

How to create subcategories
Subcategories may be created by putting onto the page that you would like to make into a subcategory. This may seem counterintuitive, because you edit the subcategory page rather than the parent category page.

Let's say that you wanted to make the category called Roses into a subcategory of the category called Flowers.


 * Step 1 - Go to the page called, and click edit this page.
 * Step 2 - Place the text   within the body of the  article, and save.
 * Finished! Roses is now a subcategory of Flowers, and will be visible on.

= Further information =

For more information about categorizing pages, see the WikiPedia article Wikipedia:Categorization.

Notes:


 * 1) We may need a page on overcategorization. Wikipedia's article links to such an article from the "when to use categories "section.
 * 2) We need an example inserted at this reference in which an article should be categorized in a category and in one of its subcategories.
 * 3) We could use an example from our own system rather than Wikipedia's.
 * 4) We need an example here.
 * 5) We need to decide whether we are going to use Wikipedia's "article is category" rather than "article is related to category" mentality. (See Wikipedia:Categorization, item 9 under "Some general guidelines.") This is huge and will determine the whole framework for classification.
 * 6) Wikipedia uses an additional feature called Classification to help users browse the category structure faster and to clarify where a category fits in this structure. For a description on Wikipedia's classification feature, click here. We do not yet employe classification because it requires a lot of maintenance if the site's category system is as embryonic and unfinished as ours is today.

Much of the text of this article came from Wikipedia's Wikipedia:Categorization, which is licensed under the GNU Free Documentation License.