Wikipedia:Categories, lists, and navigation templates

Wikipedia offers several ways to group articles: categories, lists (including embedded lists, like lists included in See also sections), and Navigational templates (of which article series boxes are one type). Each way has advantages and disadvantages, and one or more of these ways may be appropriate in a given circumstance.

These methods should not be considered to be in conflict with each other. Rather, they are synergistic, each one complementing the others. For example, since editors differ in style, some favor building lists while others favor building categories, allowing links to be gathered in two different ways, with lists often leapfrogging categories, and vice versa. This approach has resulted in two main link-based systems of navigating Wikipedia. See the navigation menu at the top of Wikipedia:Contents, and see Category:Categories. Many users prefer to browse Wikipedia through its lists, while others prefer to navigate by category; and lists are more obvious to beginners, who may not discover the category system right away. Therefore, the "category camp" should not delete or dismantle Wikipedia's lists, and the "list camp" shouldn't tear down Wikipedia's category system - doing so wastes valuable resources. Instead, each should be used to update the other.

Category workers, list builders, and series box designers all endeavor to develop comprehensive networks of links for navigating the encyclopedia. Because of this, increasingly, multiple entries to fields of knowledge are being provided. Take "symphonies", for example:

• Categories: Category:Symphonies
• Lists: List of symphonies by name
• Templates: template:Symphonies by number and name

Developers of these redundant systems should not compete against each other in a destructive manner, such as by nominating the work of their competitors to be deleted because they overlap. Doing so may disrupt browsing by users who prefer the list system. Also, lists may be enhanced with features not available to categories, but building a rudimentary list of links is a necessary first step in the construction of an enhanced list -- deleting link lists wastes these building blocks, and unnecessarily pressures list builders into providing a larger initial commitment of effort whenever they wish to create a new list, which may be felt as a disincentive.

Below is a comparison of how these techniques group information...

Categories

See also: Wikipedia:Category

Example of a category page. Every page in the article namespace should have at least one category. Categories should be on major topics that are likely to be useful to someone reading the article.

Article: Michael Jackson

Useful category: Category:American pop singers

Not useful: Category:Musicians whose first name starts with M

A category is probably inappropriate if the answer to the following questions is "no":

• Is it possible to write a few paragraphs or more on the subject of a category, explaining it?
• If you go to the article from the category, will it be obvious why it's there? Is the category subject prominently discussed in the article?

An article will often be in several categories. Restraint should be used, however — categories become less effective the more there are on a given article.

An article should usually not be in both a category and its subcategory, e.g. Microsoft Office is in Category:Microsoft software, so should not also be in Category:Software — except when the article defines a category as well as being in a higher category, e.g. Ohio is in both Category:U.S. states and Category:Ohio. (A good way to understand this exception is that if an article exists, and then a category is created on the same subject as the article, it should not cause the article to be removed from any of its categories.)

Exceptions should also be considered when the article subject has a relevance to the parent category that is not expressed by the subcategory's definition. For instance, if Category:Guillotined French Revolution figures was the only subcategory of Category:French Revolution figures, it would not make sense to remove major figures of the French Revolution solely because of the means of their death.

Categories appear without annotations, so be careful of neutral point of view (NPOV) when creating or filling categories. Unless it is self-evident and uncontroversial that something belongs in a category, it should not be put into a category. Especially see Wikipedia:Categorization of people.

An exception to the above rules is Category:Wikipedia maintenance, which contains categories intended to be temporary.

Every category should be a subcategory of some other category. You can start from the top of the category hierarchy at Category:Fundamental. If you think a good parent probably exists but you just can't find it, add the {{Uncategorized}} tag. Your category will show up at Special:Uncategorizedcategories.

For articles without any stable category, the {{Uncategorized}} tag can be used to bring attention to it, either on its own, or in the format {{uncat|<month> <year>}} (Example: {{uncat|October 2006}}) There is also an automatically updated list at Special:Uncategorizedpages which displays uncategorized/stubbed articles; however it only updates once every few days, and only lists 1000 articles at a time. So it is always best to explicitly place an {{uncat}} tag, if you are uncertain how an article should be categorized.

Advantages of categories

1. Auto-linking. Create a link to a category on an article page, and a corresponding link to that article will be visible on the category page.
2. Multi-directional navigation. A category can contain multiple subcategories, and can also be part of several categories. Categories are organized within Wikipedia into a web of knowledge starting with Category:Categories.
3. Categories are good for exploratory browsing of Wikipedia.
4. Categories are less susceptible to external linkspam than other types of pages, because only Wikipedia articles can be members of categories.
5. They are relatively unobtrusive in that they generally don't distract from the flow of the article.

Disadvantages of categories

1. Category entries are arranged in alphabetical order only (though you can control the alphabetization). They cannot be organized into sections and subsections on a single page, each with its own descriptive introduction.
2. Categories are difficult to maintain:
   1. A category with hundreds of items cannot be moved except by editing hundreds of articles (though a bot can help)
   2. Tracking changes to a category is effectively impossible:
      1. A category's edit history does not show when entries were added or removed from the category. So there is no easy way to tell when an article is removed from a category - it simply disappears with no indication that it was ever there in the first place.
      2. Wikipedia's watchlist feature is useless for tracking changes to a category's membership, because those do not show up as edits to the page (because they don't even exist on that page -- they're at the bottom of each member page).
3. Categories do not support other forms of tracking, such as adding red links. (Red links are useful as gap indicators and as task reminders to create those articles).
4. Categories give no context for any specific entry, nor any elaboration; only the name of the article is given. That is, listings cannot be annotated (with descriptions nor comments), nor referenced.
5. Alternative names for the same item can be included only by including redirects in the category.
6. It is not obvious to new users that categories exist, how to add items to them, how to link new categories into existing schemes, nor how to deal with point of view (POV) concerns.
7. Display of items in a category is limited to 200 on a page. To see the full contents of a category with more members than this, multiple pages need to be viewed.

Lists

See also: Wikipedia:Lists

Example of a list.

Advantages of lists

1. Lists are good for exploratory browsing of Wikipedia, and provide a useful alternative to the category system - lists are often more comprehensive because each is maintained from a centralized location (at the page itself). See the top end of the list hierarchy at Lists of topics, Lists of basic topics, List of overviews, and List of glossaries.
2. Lists are much easier to build (fill) than categories, because entries can be gathered, cut and pasted in from searches and other sources. Brainstorming entries from one's personal education is much easier, because you don't have to hunt for the articles to place the tags on, you simply type the topics into the list.
3. Lists can be embellished with annotations (further details). For example, a list of soccer world championship teams can include with each entry when each championship was won, who the champions defeated, who their coach was, etc.
4. Lists can be referenced to justify the inclusion of listed articles.
5. Lists can include items for which there are yet no articles (red links); or items that are not linked (see e.g. List of compositions by Franz Schubert).
6. List items can be manually sorted using a variety of methods. An article can appear several times or in different ways in the same list.
7. Lists can be linked to specific sections of articles.
8. Lists can include invisible links to discussion pages, so that clicking on "related changes" will include those (Format: [[Talk:Omphalology| ]]).
9. Lists can be more easily edited by newbies who are less familiar with Wiki markup language.
10. Images can be interspersed throughout a list.
11. Lists can be formatted in many different ways, to improve the presentation of the contents of the list.
12. Templates (such as navigation boxes) can be included as portions of a list.

Disadvantages of lists

1. No auto-linking. Every article links to its categories in a consistent way, but lists may be more difficult to discover because not every article listed links to it, and each may choose to link to it in a different way. Attempting to enforce crosslinks from articles in the category is error-prone, makes editing the list taxing, and counteracts the ease-of-editing benefits they otherwise enjoy.
2. Less comprehensive hierarchy. The category system has an extensive and detailed hierarchy to facilitate browsing by increasing specialization, while lists of lists are relatively rare and are not deeply nested.
3. Automated processing. Lists are more difficult to process automatically using bots, because they may contain prose that contains links to items that are not in the list itself, and it's necessary to parse the page wikitext to extract listed items instead of using a specialized API as categories do.
4. No automatic sorting. Editors have to manually figure out where an entry belongs, and add it there. Often editors will simply add new items to the bottom of the list, reducing the list's effectiveness.

Navigational Templates

See also: Wikipedia:Navigational templates

Example of a navigational template. Navigational templates are boxes with links to other related articles. Examples include presidents of the United States, movies in the Friday the 13th Series, or Narnia books. They are particularly useful for small and more or less complete sets; templates with a large numbers of links are not forbidden, but can appear overly busy and be hard to read and use.

The article links in a navigational template should have some ordering, whether chronological or otherwise. Alphabetical order does not provide any additional value to a category containing he same article links. It is not enough that it is possible to organize the elements of a series into a structure — that structure should itself be useful. For example, a box for characters from Buffy the Vampire Slayer by the order of listing in the opening credits is an ordering but is not useful, because it is unlikely that people would actually want to browse the articles in that order.

As with categories, all the articles in a template should substantially deal with the subject of the box. Ask yourself, is the subject of this box something that would be mentioned on every article in it?

If the answer is "no", a category or list is probably more appropriate.

If an article has multiple templates, it may be appropriate to convert some or all to categories.

For very long series, it is preferable to use incumbent series, which only show the elements of the series immediately preceding and succeeding the article.

Related pages regarding templates:

• Wikipedia:Template standardisation

For past discussion, see:

• Wikipedia:Series templates
• Wikipedia:Article series boxes policy (proposed) (rejected policy)

Advantages of navigational templates

1. Provide a consistent look and navigation system for related articles (though not between different topics — there is no standard format; though see Wikipedia:Template standardisation).
2. Faster to navigate than a category.
3. Give immediate information to equivalent elements
4. For presenting a series of articles in a chronological order, templates are often most appropriate. Example: template:Princess Royal (there are two Marys and two Annes in that list, which makes the chronological way of presenting these princesses an asset to a merely alphabetically ordered presentation of these same names)

Disadvantages of templates

1. Simple boxes can often be replaced with a category. It also can be difficult to give more detail than a category can give without the box becoming unmanageably large.
2. Templates can become ugly or pointless, e.g. by unsightly coloring schemes, size, number of them on the same page, etc. For this reason article series boxes need to be self-evident, while they can't contain much text for definitions or explanations.
3. Often inadvertently push a POV and suggest that one aspect of a topic is more important than others, being used to advertise obscure topics in prominent places, or asserting project proprietorship. Templates can go to Wikipedia:Templates for deletion if they appear to push POV. Trying to remedy this by adding more templates might lead to the disadvantage described in the previous point.
4. Can alter the page lay-out without the reason thereof showing on the page itself (e.g. when the template contains a NOTOC instruction, an unclosed div, etc.)
5. Templates work best when they are not substed. However, this increases server load.