Wikipedia:Categorization - Wikipedia
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(Redirected from
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Wikipedia editing guideline
"WP:CATEGORY", "WP:CAT", and "WP:CG" redirect here. For the list of top-level categories, see
Wikipedia:Contents/Categories
. For the gadget, see
Wikipedia:HotCat
. For the WikiProjects, see
Wikipedia:WikiProject Cats
Wikipedia:WikiProject Categories
, and
Wikipedia:WikiProject Computer graphics
. For the category system itself, see
Category:Contents
. For technical information on categories, see
Help:Category
. For quick answers, see
Wikipedia:FAQ/Categorization
This page documents an English Wikipedia
editing guideline
Editors should generally follow it, though
exceptions
may apply.
Substantive
edits to this page
should reflect consensus
Shortcuts
WP:CAT
WP:CAT
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WP:CATEGORY
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The primary purpose of the
categorization
system on Wikipedia is to provide navigational
links
within a structured,
tree-like hierarchy
of
categories
. By grouping pages according to their essential,
defining
characteristics, the system allows readers to browse and efficiently locate related topics.
Proposals to delete, merge, or rename categories should follow the process outlined at
Wikipedia:Categories for discussion
. Please use that forum before undertaking extensive re-categorization of existing categories or the mass creation of new ones.
Categorizing pages
A screencast showing how to categorize pages and explaining the usage of the
tool
HotCat
Further information:
Help:Category
See also:
Wikipedia:Categorization dos and don'ts
and
Wikipedia:Categorizing redirects
Every
Wikipedia page
should belong to at least one category, except for
talk pages
redirects
, and
user pages
, which may optionally be placed in categories where appropriate.
Shortcut
WP:CATSPECIFIC
WP:CATSPECIFIC
Each categorized page should be placed only in the
most specific
categories to which it logically belongs, and
subcategories
should be categorized under only the
most specific
parent categories
possible.
Important:
All categories form part of a
tree-like hierarchy
. Do not add categories to pages as if they are
tags
Creating category pages
Shortcut
WP:CREATECAT
WP:CREATECAT
Sometimes proper categorization requires the creation of a new category.
Before creating a new category
Shortcut
WP:BEFORECAT
WP:BEFORECAT
Main pages:
Wikipedia:Categories, lists, and navigation templates
and
Wikipedia:Overcategorization
See also:
Help:Sortable tables
Categories are not the only means of allowing users to browse sets of related pages, and have
several disadvantages
, including:
Categories only show the
name
of each page being categorized. While the
category description
may provide information about the category in general, individual category members cannot be annotated with descriptions or comments, so they give no context or elaboration for any specific entry.
There is no provision for
providing references
for any given page in a category, making it difficult to
verify
that a page meets the category's criteria of inclusion.
So, consider whether a
list
would be more appropriate than a category (or in addition to a category) for a grouping of pages. As examples, a
list of Nobel laureates
could include dates, and a list formatted as a
table
can provide options for sorting the entries.
Also consider whether the proposed category might be considered "
category clutter
", as described in
Wikipedia:Overcategorization
Choosing a name for the category
Shortcut
WP:CATNAME
WP:CATNAME
Main page:
Wikipedia:Category names
Further information:
§ Naming conventions
A good category name is accurate and
neutral
, and, as much as possible, defines the category's inclusion criteria in the name itself.
Important:
Moving non-conventionally categorized pages to another category name (see
{{
Category redirect
}}
) imposes an additional overhead – an edit for
every
categorized page and subcategory. So, when choosing a name for the category, please be sure a category with a similar name or similar inclusion criteria does not already exist. (See also:
WP:OVERLAPCAT
.)
One way to determine if suitable categories already exist for a particular page is to check the categories on pages concerning similar or related topics. You can also search existing category names as described
here
(top of page).
For example: You might want to add a subcategory for people to
Category:Mexicans
. By starting at
Category:People by nationality
, you will discover that Mexicans are placed in
Category:Mexican people
Note:
Eponymous categories
(categories whose name and topic is the same as an article, such as a category named after a person) should only be created if enough directly related articles exist.
Creating the category
After you have determined an appropriate category name for the category, next try to find a suitable place for the new category. (For example, categories of people should be in the
tree of "people" categories
.) Please see
§ Category tree organization
for more information on this.
Once you have determined where to categorize this new category, you should be ready to create the new category.
To create a category:
Add a page to the intended category. Do this by editing that page, and add the name of the new category: (e.g.
[[Category:New category name]]
Shortcut
MOS:CATORDER
MOS:CATORDER
Per
MOS:ORDER
, categories are placed at the end of the wikitext, but before any
stub
templates, which transclude their own categories.
Eponymous categories
should appear first. Beyond that, the order in which categories are placed on a page is not governed by any single rule (for example, it does not need to be alphabetical, although partially alphabetical ordering can sometimes be helpful). Normally the most essential, significant categories appear first.
Save your edit. The as-yet-undefined category name will now appear as a
red link
in the category list at the bottom of the page.
Shortcut
WP:CATREDLINK
WP:CATREDLINK
A page should never be left with a non-existent (
red-linked
) category on it. Either the category should be created, or else the link should be removed or changed to a category that does exist.
Next, click on that red link, which brings you to the new category page to create.
Finally, at the bottom of the category page, simply add a parent category (e.g.
[[Category:Parent category name]]
), which should usually be a
hypernym
of the subcategory. This will add the new category into the appropriate parent category. (A category can have more than one parent category.)
Important:
If something goes wrong, double check to see if you followed the steps properly and check if the wikitext is correct. For example, if the category fails to list in the parent category, the wikitext should be
[[Category:Parent category name]]
, not
[[:Category:Parent category name]]
Category description
Shortcut
WP:CATDESC
WP:CATDESC
While it should typically be clear from the name of an existing category which pages it should contain, sometimes, a common-sense guess based on the name of the category is not enough to figure out whether a page should be listed in the category. So, rather than leave the text of a category page empty (other than parent categories), adding a
hatnote
linking to the main article or another page which describes the topic (see
§ Articles with eponymous categories
) can help with that.
However, only linking to a Wikipedia article explaining the title is often not sufficient as a description for a category. It can be helpful – to both readers and editors – to include a clear description of the category, indicating what pages it should contain, how they should be subcategorized, and so on, and linking to one or more pages as background information.
In such cases, the desired contents of the category should be described on the category page, similar to how the
list selection criteria
are described in a stand-alone list. The category description should make direct statements about the criteria by which pages should be selected for inclusion in (or exclusion from) the category. This description, not the category's name, defines the proper content of the category. Do not leave future editors to guess about what or who should be included from the title of the category. Even if the selection criteria might seem obvious to you, an explicit standard is helpful to others, especially if they are less familiar with the subject.
The description can also contain links to other Wikipedia pages, in particular to other related categories that do not appear directly as subcategories or parent categories, and to relevant categories at
sister projects
, such as
Commons
Like
disambiguation pages
, category pages should contain neither
citations
nor
external links
Various templates have been developed to make it easier to produce category descriptions; see
Category namespace templates
and
Wikipedia:Category classification templates
. There are hatnote templates including
{{
Category main article
}}
and
{{
Category see also
}}
; others are listed at
Wikipedia:Hatnote#Categories
Additional considerations
Categories may have hundreds or thousands of members, displayed over many pages, with up to 200 entries on a single page. To make navigating large categories easier, a table of contents can be used on the category page. The following templates are some of the ways of doing this:
{{
Category TOC
}}
– adds a complete table of contents (Top, 0–9, A–Z)
{{
Large category TOC
}}
– adds a complete table of contents with five subdivisions for each letter (Aa Ae Aj Ao At)
See
Wikipedia category table of contents templates
for more options.
Consider using
{{
Automatic category TOC
}}
, which automatically generates the appropriate TOC for the number of pages in a category.
Likewise, a maximum of 200 subcategories are displayed at a time, so some subcategories may not be immediately visible. To display all subcategories at once, add a category tree to the text of the category page, as described at
Help:Category § Displaying category trees and page counts
Category pages can have interlanguage links to corresponding categories in other language Wikipedias. Edit these on
Wikidata
by following the instructions at
Help:Interlanguage links
Categorizing articles
For category types to avoid, see
Wikipedia:Overcategorization
In general, categories of articles must be:
Shortcuts
WP:CAT#V
WP:CAT#V
WP:CATV
WP:CATV
Verifiable
: It should be clear from verifiable information in the article why it was placed in each of its categories. Use the
{{
Unreferenced category
}}
template if you find an article in a category that is not shown by sources to be appropriate or if the article gives no clear indication for inclusion in a category.
Shortcuts
WP:CAT#N
WP:CAT#N
WP:CATPOV
WP:CATPOV
WP:POVCAT
WP:POVCAT
Neutral
: Categories appear on article pages without annotations or direct citations to justify or explain their addition; editors should be conscious of the need to maintain a neutral point of view when creating categories or adding them to articles. Categorizations should generally be uncontroversial; if the category's topic is likely to spark controversy, then a
list article
(which can be annotated and referenced) is probably more appropriate.
For example, a politician (not convicted of any crime) should not be added to a category for criminals.
Shortcuts
WP:CAT#D
WP:CAT#D
WP:CATDEF
WP:CATDEF
Defining
: Defining characteristics of an article's topic are central to categorizing the article. A defining characteristic is one that
reliable sources
commonly
and
consistently
refer to
in describing the topic, such as the nationality of a person or the geographic location of a place.
Articles should normally be included in the categories that are most closely related to the subject's defining characteristics.
For example,
Italian
and
artist
are defining characteristics of
Caravaggio
, because virtually all reliable sources on the topic mention them, so that article is included in categories such as
Category:Italian Baroque painters
Categories should not group subjects by
trivial characteristics
that have little relevance to the topics, unless it can be shown that such a characteristic or grouping is notable.
For example,
Category:Italian people with dark eyebrows
would likely be trivia, even if it's true, so the category does not exist, and
Caravaggio
is not in it.
For
characteristics that are neither defining nor trivia
, editors should use their judgment to choose which additional categories (if any) to include.
For example,
Caravaggio
is included in the non-defining category of
Category:Deaths from sepsis
Naming conventions
For the full category naming guidelines (including topic-specific naming conventions), see
Wikipedia:Category names
Standard
article naming conventions
apply: Generally, category names are based on what the subject is called in
verifiable
reliable sources
(particularly for
technical subjects
), so that those sources may be used to support the inclusion of information. When this offers multiple possibilities, editors choose among them by considering
several principles
: the ideal category name uses words and phrases which
precisely
identify the subject; it is
neutral
, short, natural, distinguishable and recognizable; and resembles names for similar categories.
Avoid
subjective adjectives
such as
famous
large
, or
beautiful
in category titles.
Avoid
abbreviations
. For example:
Category:Military equipment of World War II
not
Category:Military equipment of WW2
. However,
acronyms
that have become the official, or generally used, name (such as
NATO
) should be used where there are no other conflicts. Exceptions to this should be explained in the
category description
Because no two categories can have the same title, it is sometimes necessary to add distinguishing information, often in the form of a description in
parentheses
after the name. When an article on a topic requires
disambiguation
, any
category named for that topic
should include the same form of disambiguation, even if there are no other categories that share the name. A subcategory should generally use the same disambiguation as its parent category, even if the name would not be ambiguous. For example,
Washington (state)
has the categories
Category:Washington (state)
and
Category:Washington (state) legislative districts
(even though there is an article at
Washington legislative districts
).
Naming guidelines for subcategories of
Category:Stub categories
are listed at
Wikipedia:WikiProject Stub sorting/Naming conventions § Stub categories
Topic and set categories
Topic categories
are
named after a topic
(usually corresponding to the name of a Wikipedia article), and should be singular.
For example,
Category:France
contains articles relating to the topic
France
. Other examples:
Category:Law
Category:Hillary Clinton
Set categories
are named after a class, and should be plural. A category may be explicitly labeled as such using the
{{
Set category
}}
template.
For example,
Category:Cities in France
contains articles whose subjects are cities in France. Other examples:
Category:Writers
Category:Villages in Poland
Note that in some instances a topic category and a set category may have similar names – the topic category name is singular and the set category name is plural. Be careful to choose the right one when categorizing articles.
For example,
Category:Opera
is a topic category (containing all articles relating to the topic), while
Category:Operas
is a set category (containing articles about specific operas).
Sometimes, for convenience, the two types can be combined to create a
set-and-topic
category.
For example,
Category:Voivodeships of Poland
contains articles about particular voivodeships as well as articles relating to voivodeships in general.
Categorizing articles about people
Shortcut
WP:SEPARATE
WP:SEPARATE
Main page:
Wikipedia:Categorizing articles about people
See also:
Category:People
For articles about people, categorize by characteristics of the person the article is about,
not
characteristics of the
article
: e.g. do not add
Category:Biography
Subcategories
of
Category:Biography (genre)
may legitimately contain articles about biographical
films
or biographical
books
, but should not contain articles about individual people. The
article
is a biography; the topic of the article – the
person
– is not.
Keep articles about people separate. Categories with a title indicating that the contents are people should normally only contain biographical articles and lists of people, and perhaps a non-biographical main article, though this can instead be linked in the category description. This is for clarity and ease of use, and to preserve the integrity of the
category tree of people articles
Editors should take particular care when categorizing
articles about
living people
. All quotations and any material
challenged or likely to be challenged
must be supported by an
inline citation
to a
reliable
, published source. Contentious material about living (or, in some cases, recently deceased) persons that is unsourced or poorly sourced—whether the material is negative, positive, neutral, or just questionable—must be
removed immediately and without waiting for discussion
Categorizing articles about works
Shortcuts
WP:CATWORKS
WP:CATWORKS
WP:CATFICTION
WP:CATFICTION
See also:
Category:Creative works
and
Wikipedia:Category names § Works of art categories by subject
Articles on fictional subjects should not be categorized in a manner that confuses them with real subjects.
{{
Category see also
}}
is useful for interlinking examples of real-world and fictional phenomena.
Individual
works by a person
should not be included in an
eponymous category
but should instead be in a subcategory such as
Category:Novels by Agatha Christie
Works should be placed in categories about works, not in categories for elements of those works. For example, the television series
Cow and Chicken
should be placed in
Category:Television series about chickens
, not in
Category:Fictional chickens
Categorizing list pages
See also:
Category:Lists
If there are more than a few
lists
in a particular subject area, it may be appropriate to create a specific subcategory that contains only the list pages and no other types.
For example,
Category:Countries
contains the subcategory
Category:Lists of countries
, which in turn contains the list pages
List of rugby union playing countries
and
List of countries with multiple capitals
When placing list pages in a lists category, use a
sort key
to adjust the page title to exclude the starting words "List of", otherwise all lists would appear under "L".
For example, when adding
List of rugby union playing countries
to
Category:Lists of countries
, using
[[Category:Lists of countries|Rugby union]]
will sort it in the R section.
Eponymous categories
Shortcuts
WP:EPON
WP:EPON
WP:EPONYMOUS
WP:EPONYMOUS
See also:
Category:Eponymous categories
and
Category:Wikipedia categories named after people
"WP:EPONYMOUS" redirects here. For overuse of the word "eponymous" on Wikipedia, see
WP:TITULAR
A category that covers exactly the same topic as an article is known as the
eponymous category
for that article (e.g.
New York City
and
Category:New York City
Mekong
and
Category:Mekong River
Abraham Lincoln
and
Category:Abraham Lincoln
).
An eponymous category is generally named the same as its main article, but exceptions sometimes apply. See
§ Naming conventions
for more information.
Shortcut
WP:OCEPON
WP:OCEPON
Eponymous categories should
not
be created unless enough directly related articles or subcategories exist. However, this should not be done simply to reduce the number of categories displayed in an article.
An eponymous category should have only the categories of its article that are relevant to the category's content. For example:
Both
New York City
and
Category:New York City
fit well in
Category:Cities in New York (state)
The article
New York City
is in
Category:Populated places established in 1624
, but this category is not necessarily relevant to all the contents of
Category:New York City
, so it should not be used on the eponymous category.
Articles with eponymous categories
Shortcut
WP:CATMAIN
WP:CATMAIN
"WP:CATMAIN" redirects here. For the template, see
Template:Category main article
The article itself should be a member of the eponymous category. It should be sorted with a space, so that it appears at the start of the category listing (see
§ Sort keys
below).
The article should be linked on the category page as the main article of the category using the
{{
Category main article
}}
template.
Articles with an eponymous category may be categorized in the broader categories that would be present if there were no eponymous category (e.g. the article
France
appears in both
Category:France
and
Category:Countries in Europe
, even though the latter category is the parent of the former category). Editors should decide by
consensus
which solution makes most sense for a category tree. There are three options:
Keep both the eponymous category and the main article in the parent category. This is used in
Category:Countries in Europe
to allow that region's country articles to be navigated together.
Keep just the article in the parent category. This is used in
Category:British Islands
, to prevent a
loop
Keep just the eponymous category in the parent category. This is used for
Category:Farmers
in
Category:People by occupation
. Such "
by
" categories sometimes cover a limited navigational set, not a topic (see
§ Category tree organization
below), thus there is no logical article content.
If eponymous categories are categorized separately from their articles, it will be helpful to make links between the category page containing the articles and the category page containing the eponymous categories. The template
{{
Category see also
}}
can be used for this. An example of this set-up is the linked categories
Category:American politicians
and
Category:Wikipedia categories named after American politicians
Categorizing draft pages
Shortcuts
WP:CATDRAFT
WP:CATDRAFT
WP:DRAFTNOCAT
WP:DRAFTNOCAT
Further information:
Wikipedia:Drafts § Preparing drafts
See also:
Category:Wikipedia drafts
Drafts, no matter whether in the
draft namespace
or
your userspace
, are not articles and thus do not belong in
content categories
such as
Category:Living people
or
Category:Biologists
. If you copy an article from
mainspace
to draftspace or userspace and it already contains categories, disable those categories. This can be done in any of the following four ways (but only the first two ways are recommended, as a disadvantage of the last two ways is that the categories will not be linked on the page):
Wrapping them in
{{
Draft categories
}}
{{
Draft categories
[[
Category
Living people
]]
[[
Category
Biologists
]]
}}
Inserting a colon character to
link to each category
(e.g. changing
[[
Category
Biologists
]]
to
[[
:Category
Biologists
]]
).
Commenting
) them out (e.g.
).
Wrapping them in
tags (e.g.
nowiki
[[Category:Living people]] [[Category:Biologists]]
nowiki
).
After you move the draft into article space, remove the leading colons, uncomment out the categories or remove the
tags to re-enable the categories. If you use the draft categories template, the categories will automatically work as normal in mainspace, but the template should be removed. The same system may be used in a new draft to list the categories it may have when moved to mainspace.
Two scripts are available to help with these tasks:
User:DannyS712/Draft no cat
and
User:DannyS712/Draft re cat
Categorizing project pages
Shortcut
WP:PROJCATS
WP:PROJCATS
Wikipedia administrative categories
Further information:
Wikipedia:Administration § Data structure and development
, and
Wikipedia:Wikipedia namespace
See also:
Category:Wikipedia administration
A distinction is made between two types of categories:
Administrative categories – intended for use by editors or automated tools, based on features of the current state of articles, or used to categorize non-article pages.
Content categories – intended as part of the encyclopedia, to help readers find articles, based on features of the subjects of those articles.
Administrative categories include
stub categories
(generally produced by
stub
templates),
maintenance categories
(often produced by
cleanup templates
such as
{{
Cleanup
}}
and
{{
Citation needed
}}
, or those used for
maintenance
projects), and
categories of pages in non-article
namespaces
, such as
WikiProject
assessment
categories
and
categories
holding
Wikipedia policies and guidelines
Article pages should be kept out of administrative categories if possible. For example, the templates that generate WikiProject and assessment categories should be placed on talk pages, not on the articles themselves. If it is unavoidable that an administrative category appears on article pages (usually because it is generated by a maintenance template that is placed on articles), then in most cases the category should be made a
hidden category
, as described in
§ Hiding categories
below.
Maintenance categories should never be added to articles directly. Instead, the categories should be
added using templates
There are separate administrative categories for different kinds of non-article pages, such as
project page
categories,
template
categories,
disambiguation page categories
, etc.
In some administrative categories, pages may be included regardless of type or namespace. For example, in an error-tracking category, it makes sense to group templates separately, because addressing the errors there may require different skills compared to fixing an ordinary article. For sorting each namespace separately, see
§ Sort keys
below.
Files
Shortcut
WP:FILECAT
WP:FILECAT
Further information:
Wikipedia:Manual of Style/Images § Image description pages
Category tags should be added to
file
pages of files that have been uploaded to Wikipedia. When categorized, files are not included in the count of articles in the category, but are displayed in a separate section with a thumbnail and the name for each. A category can mix articles and images, or a separate file/image category can be created. A file category is typically a subcategory of the general category about the same subject, and a subcategory of the wider category for files,
Category:Wikipedia files
. To categorize a new file when uploading, simply add the category tag to the
upload summary
Freely licensed files should be uploaded to, and categorized on,
Wikimedia Commons
, instead of uploading and categorizing on Wikipedia. Existing freely licensed files should usually be moved from Wikipedia to Commons, with a mirror page automatically remaining on Wikipedia. (For an example of one such mirror page, see
here
.) Categories should not be added to these Wikipedia mirror pages, because doing so creates a new Wikipedia page that is subject to
speedy deletion
. Exceptions to this principle are made for mirror pages of images that are nominated as
featured pictures
and for those that appear on the Wikipedia
Main Page
in the
Did You Know?
column.
Images that are used in Wikipedia that are
non-free or fair use
should not appear as thumbnail images in categories. To prevent the thumbnail preview of images from appearing in a category,
__NOGALLERY__
should be added to the text of the category. In such cases, the file will still appear in the category, but the image preview will not.
Templates
Shortcut
WP:CAT#T
WP:CAT#T
See also:
Template:Documentation
Templates
are not articles and thus do not belong in
content categories
. They should, however, be placed in
template categories
– subcategories of
Category:Wikipedia templates
– to assist when looking for templates of a certain type. For example,
Template:The Beatles albums
is categorized under
Category:England rock music group navigational boxes
, which is ultimately a subcategory of
Category:Music navigational boxes
(type), but
Template:The Beatles albums
should
not
be categorized under
Category:The Beatles
or
Category:Albums
(content).
Pages using a template should rarely be placed in the same categories as the template itself. To ensure a template's categories are not applied to a page using the template, template categories should be placed on the template's
documentation page
, normally after the two pipes in a
includeonly
>{{
Sandbox other
||
...
}}includeonly
block. Because template documentation is rarely
protected
, template categorization can be modified by all editors even when the template code itself is protected from editing by most editors. When there is no documentation page, the categories for the template may be placed at the bottom of the template itself, within a
block. There should be no spaces or new lines between the last part of the template proper and the opening
tag.
User pages
Shortcuts
WP:CAT#USER
WP:CAT#USER
WP:USERNOCAT
WP:USERNOCAT
Further information:
Wikipedia:User categories
and
Wikipedia:User pages § Categories, templates that add categories, and redirects
User pages
are not articles and thus do not belong in
content categories
such as
Category:Living people
or
Category:Biologists
. Similarly,
draft
versions of articles should be kept out of content categories. Also, do not
transclude
full articles into your user pages, as this will result in the user page being included in all the article's categories.
You also may not leave userspace pages sitting in red-linked categories that do not exist. Although it may seem less serious than mixing userspace content with mainspace content in conventional categories, red-linked categories in userspace get picked up by the category cleanup reports just the same as red-linked categories in mainspace, and thus actively disrupt the process of cleaning up mainspace category errors. The sole exception is that you
are
allowed to file your user page in
Category:Wikipedians with red-linked categories on their user page
, a harmless joke category that consensus has deemed a standalone exception to the rule – however, you must use that exact category itself, and are not free to use differently worded or differently spelled variants of it, and your page cannot be left in any other red-linked categories besides that.
However, user pages can optionally be placed in
user categories
– subcategories of
Category:Wikipedians
, such as
Category:Wikipedian biologists
– which assist collaboration between users. Also, certain
user sub-pages
that are non-article drafts are permitted in
project categories
, such as
Category:User essays
Note also that Wikipedia policy around
ownership of content
means that other editors
are
allowed to edit pages in your personal userspace. If your page is in categories that it cannot be in under USERNOCAT, other editors are free to remove it from those categories and do not need to ask you for permission to edit "your" content.
A list of article-space categories with user pages is maintained at
Wikipedia:Database reports/Polluted categories
Categorization using templates
Shortcuts
WP:TEMPLATECAT
WP:TEMPLATECAT
WP:TCAT
WP:TCAT
Many
templates
include category declarations in their transcludable text, for the purpose of
placing the pages containing those templates into specific categories
. This technique is very commonly used for populating certain kinds of administrative categories, including stub categories and maintenance categories. See
Template:Infobox roller coaster
for an example that only adds a category by manufacturer if it exists, and otherwise uses a hidden category.
However, it is recommended that articles not be placed in ordinary
content
categories using templates in this way. There are many reasons for this: editors cannot see the category in the wikitext; removing or restructuring the category is made more difficult (partly because automated processes will not work); inappropriate articles and non-article pages may get added to the category;
sort keys
may be unavailable to be customized per category; and ordering of categories on the page is less controllable.
When templates are used to populate administrative categories, ensure that the code cannot generate nonsensical or non-existent categories, particularly when the category name depends on a parameter.
See
Wikipedia:Category suppression
for ways of keeping inappropriate pages out of template-generated categories.
Category declarations in templates often use
{{PAGENAME}}
as the sort key, because this overrides any
DEFAULTSORT
defined on the page.
Redirecting categories
Shortcut
WP:CATRED
WP:CATRED
"WP:CAT-R" redirects here. For the guideline on categorizing page redirects, see
Wikipedia:Categorizing redirects
"WP:CATRED" redirects here. For the guideline on red-linked categories, see
WP:REDNOT
For an essay on this topic, see
Wikipedia:Category redirects that should be kept
See also:
Category:Wikipedia soft redirected categories
Do
not
create inter-
category
redirects by adding
#REDIRECT [[Target page]]
to a category page. Unlike when
renaming articles
, categories cannot be
redirected
using "hard" redirects. Articles added to a redirected category will not show up in the target category. And since redirected categories do not become "
red links
", editors will not be aware when they add an article to a redirected category.
Instead, a form of "
soft redirect
" may be used in limited circumstances. You can create a
category redirect
by adding
{{
Category redirect
|target}}
to the category page.
Bots
patrol these categories and move articles to the "target" of the redirect.
If you need to add a
redirect category
to a
{{
Category redirect
}}
, use the template's second parameter. For example:
{{
Category redirect
Years of the 19th century in Ceylon
{{
R from category navigation
}}
{{
R from template-generated category
}}
}}
Category redirects are
costly
. While placing a page in a category redirect is not a
big
problem, it
is
a problem. There are
plenty of helpful uses of category redirects
, but category redirects are not as
cheap as regular redirects
. Links to article redirects are
not broken
: i.e. click on the link and you are automatically redirected to its target. However, links to category redirects
are
broken and need to be fixed, except when resolved by a template (i.e. the template generates categories using a pattern, and some of the resulting category names are intentionally resolved by the use of
{{
Resolve category redirect
}}
within the template, as in the Ceylon example above). Placing a page into a category redirect makes it show up in the category redirect – not its target – until a bot comes along and fixes the link.
Shortcut
WP:DISAMBIGCAT
WP:DISAMBIGCAT
If a category is renamed because it is ambiguous, and categories exist for two or more meanings, then create a category
disambiguation page
at the old name, using
{{
Category disambiguation
}}
. See also
Category:Disambiguation categories
Note:
Usually only do this at an unused category name which is ambiguous, e.g.
Category:Lewis
. If an ambiguous name is used for an active category because it is clearly the
primary topic
, and there are only one or two other categories with similar names, use a hatnote like the one at
Category:Lewes
. For longer lists, we can also create pages such as
Category:Bedford (disambiguation)
Hiding categories
Shortcut
WP:HIDDENCAT
WP:HIDDENCAT
In cases where, for technical reasons, administrative categories appear directly on articles rather than talk pages, they should be made into
hidden categories
, so that they are not displayed to readers. This rule does not apply to
stub
categories – these are
not
hidden.
To hide a category, add the template
{{
Maintenance category
|hidden=yes}}
to the category page (the template uses the
magic word
__HIDDENCAT__
). This also places the page in
Category:Hidden categories
A logged-in user may elect to view all hidden categories, by checking "Show hidden categories" in the "Appearance" tab of their
Preferences
. "Hidden" parent categories are never in fact hidden on category pages (although they are listed separately).
Hidden categories are listed at the bottom when previewing. All users of the desktop version can see hidden categories for a page by clicking "Page information" on the right-hand side, or by editing the whole page with the source editor.
For more information, see
mw:Help:Categories § Hidden categories
Categorizing stub articles
Shortcut
WP:CAT#STUB
WP:CAT#STUB
Main page:
Wikipedia:Stub § New stub categories
Stub templates
categorize stub articles for maintenance purposes into
administrative categories
, not for user browsing, so they do
not
count as categorization for the purposes of Wikipedia's categorization policies. An article which has a "stubs" category on it
must
still be filed in the most appropriate content categories, even if one of them is a direct parent of the stubs category in question.
Category tree organization
See also:
Category:Contents
Tree structure
, and
Tree (data structure)
Shortcut
WP:CAT#TREE
WP:CAT#TREE
Partial view of Wikipedia's category system from 2007. Arrows point from category to subcategory.
Categories are organized as overlapping "
trees
", formed by creating links between inter-related categories (in mathematics or computer science this structure is called a
partially ordered set
).
There is one top-level category:
Category:Contents
. All other categories are subcategorized below this category.
tree structure
showing the possible hierarchical organization of an encyclopedia
An item may belong to several subcategories of a parent category (as pictured).
Subcategorization
Shortcuts
WP:SUBCAT
WP:SUBCAT
WP:PARENTCAT
WP:PARENTCAT
If logical membership of one category implies logical membership of a second category (an
is-a
relationship), then the first category should be made a subcategory (directly or indirectly) of the second category (the "parent" category). Any category may potentially contain (or "branch into") subcategories.
A is said to be a
parent category
of B when B is a
subcategory
of A.
When making one category a subcategory of another, ensure that the members of the subcategory really can be expected (with possibly a few exceptions) to belong to the parent also.
For example,
Cities in France
is a subcategory of
Populated places in France
, which in turn is a subcategory of
Geography of France
A subcategory may potentially have two or more parent categories.
For example,
Category:British writers
would be in both
Category:Writers by nationality
and
Category:British people in arts occupations
If two categories are closely related but are not in a subset relation, then links between them can be included in the
category description
of the category pages.
Pages (and subcategories) should not usually be placed in both a given category and any of its subcategories or parent categories. For some exceptions to this, see
§ Eponymous categories
and
§ Non-diffusing subcategories
For example, the article
Paris
need only be placed in
Category:Cities in France
not
also in
Category:Populated places in France
. Because the first category (cities) is in the second category (populated places), readers are already given the information that Paris is a populated place in France by it being a city in France.
Recursive categorization
Shortcut
WP:CATLOOP
WP:CATLOOP
"WP:CATLOOP" redirects here. For a list of category loops, see
User:SDZeroBot/Category cycles
Category
chains
formed by parent–child relationships should never form closed loops;
that is, no category should be contained as a subcategory of one of its own subcategories.
There is an exception to this for maintenance purposes. For example,
Category:Hidden categories
is a direct subcategory of itself and of
Category:Wikipedia extended-confirmed-protected pages
and
Category:Container categories
, each of which is a direct subcategory of
Category:Hidden categories
Diffusing large categories
"WP:DIFFUSE" redirects here. For conflicts, see
Wikipedia:Diffusing conflict
Shortcut
WP:DIFFUSE
WP:DIFFUSE
Although there is no limit on the size of categories, a large category will often be broken down ("diffused") into smaller, more specific subcategories. For example,
Category:Rivers of Europe
contains no articles about specific rivers directly; they are all in subcategories.
A category may be diffused using several coexisting schemes; for example,
Category:Albums
is broken down by artist, by date, by genre, etc.
Metacategories
may be created as ways of organizing schemes of subcategories. For example,
Category:The Beatles albums
is not placed directly into
Category:Albums
but into the metacategory
Category:Albums by artist
, which itself appears in
Category:Albums by person
then
Category:Albums
. (See
Category:Categories by parameter
.)
It is possible for a category to be only partially diffused – some members are placed in subcategories, while others remain in the main category.
Information about how a category is diffused may be given on the category page. Categories which are intended to be fully broken down into subcategories can be marked with the
{{
Category diffuse
}}
template, which indicates that any pages which editors might add to the main category should be moved to the appropriate subcategories when sufficient information is available. (If the proper subcategory for an article does not exist yet, either create the subcategory or leave the article in the parent category for the time being. However, avoid creating
subcategories for just one article
.)
To suggest that a category is so large that it ought to be diffused, or substantially diffused, into subcategories, you can add the
{{
Overpopulated category
}}
template to the category page.
Non-diffusing subcategories
Shortcuts
WP:CAT#NON-DIFFUSE
WP:CAT#NON-DIFFUSE
WP:ALLINCLUDED
WP:ALLINCLUDED
WP:DUPCAT
WP:DUPCAT
Not all subcategories serve the "diffusion" function described above; some are simply subsets which have some special characteristic of interest, such as
Best Actor Academy Award winners
as a subcategory of
Film actors
. They provide an exception to the general rule that pages are not placed in both a category and its subcategory: there is no need to take pages out of the parent category
purely
because of their membership of a non-diffusing subcategory. (Of course, if the pages also belong to other subcategories that do cause diffusion, then they will not appear in the parent category directly.)
Non-diffusing categories should be identified with a template on the category page:
{{
Non-diffusing subcategory
}}
should be used on non-diffusing subcategories, such as
Category:American novelists of Asian descent
{{
Non-diffusing parent category
}}
can be used on a parent category of a non-diffusing subcategory.
{{
All included
}}
can be used for categories where all child articles of a certain type are in the parent, such as
Category:Presidents of the United States
Subcategories defined by gender, ethnicity, religion, and sexuality should almost always be non-diffusing subcategories to prevent
othering
. The
Wikipedia:Categorizing articles about people
guideline outlines the rules on these categories in more detail.
Note that some categories can be non-diffusing on some parents and diffusing on others. For example,
Category:British women novelists
is a non-diffusing subcategory of
Category:British novelists
, but it is a diffusing subcategory of
Category:Women novelists by nationality
{{
Diffusing subcategory
}}
can be used with
{{
Non-diffusing subcategory
}}
to specify which parents the subcategory does and does not diffuse.
Sort keys
Shortcut
WP:SORTKEY
WP:SORTKEY
"WP:Sorting" redirects here. For sorting of tables, see
Help:Sortable tables
Further information:
Wikipedia:Categorization/Sorting names
By default, a category page will list its member pages and subcategories alphabetically by their page titles. Sometimes, this is undesirable, so
sort keys
are needed to produce a better ordering. A sort key can be added to a page using the
magic word
{{
DEFAULTSORT
sort key
}}
, which will cause the page to be sorted in categories under a different specified title. (Per
MOS:ORDER
, this is placed just before the list of category declarations.) The page title and DEFAULTSORT can also be overridden for individual categories using the same syntax as
piped links
[[Category:
category name
sort key
]]
. For the mechanics, see
Help:Category § Sorting category pages
People are usually sorted by last name rather than first name, so "Last name, First name" sort keys are used (e.g.
Washington, George
for
George Washington
).
There are many other rules for sorting people's names; for more information, see
Wikipedia:Categorization/Sorting names
Other sort key considerations (in no particular order):
In English Wikipedia, sort order merges (ignores) case and
diacritics
. For example, "Baé", "Båf", "BaG" would be sorted in that order.
The main article(s) of a category, if existent, should have a space as the sort key so that they appear at the very top of the category (e.g.
[[Category:Example| ]]
). Those articles are typically homonymous or at least synonymous to their category. This is generally limited to one or two articles in a category.
Other general articles that are highly relevant to the category should be sorted with an asterisk as key so that they also appear near the top of a category but beneath the main articles. Example:
[[Category:Example|*]]
Those articles are typically called things like "List of example", "Outline of example", "Index of example" or similar. This is generally limited to a few articles in a category, and there may not be any. This is also often used to sort lists categories within relevant parent categories.
Use other sort keys beginning with a space (or an asterisk, plus sign, etc.) for any other pages that should appear
after
the main article and
before
the ordinary alphabetical listings. The same technique is sometimes used to bring particular subcategories (such as
metacategories
) to the start of the list.
Sort order of characters
before
numbers and Latin alphabet (0–9, A–Z) is (partial list):
_ - – — , ; : ! ? . ' " ( ) [ ] { } @ * / \ & # % • ` ^ + ÷ × < = > | ~ − $
Leading articles
an
, and
the
– are among the most common reasons for using sort keys, which are used to transfer the leading article to the end of the key, as in
{{DEFAULTSORT:Lady, The}}
. Please also apply these sort keys to deliberate misspellings of these words (e.g.
da
or
tha
for
the
), as well as foreign language leading articles, such as
el
or
der
(but beware of non-article words that have the same spelling, e.g. words that translate as
at
or
one
). However, leading articles in foreign-language-derived names which are no longer translated in English are not subject to this rule; e.g. the sort key for
El Paso
should be left as the default value (i.e. no {{DEFAULTSORT}} required).
Spell out abbreviations and characters used in place of words so that they can be found easily in categories. For example, the sort key for
Mr. Bean
should be
{{DEFAULTSORT:Mister Bean}}
, and
Dungeons & Dragons
should be sorted as
{{DEFAULTSORT:Dungeons and Dragons}}
. An exception is the times sign (×) as in "Men's 4 × 100 metre" relay; use the letter
in this case.
Landforms (and similar) that have noun prefixes such as
Isle of Mull
should have the noun sorted after as
{{DEFAULTSORT:Mull, Isle of}}
. However, this is not usually done for settlements and administrative divisions; for example, while
Isle of Wight
uses {{DEFAULTSORT:Wight, Isle of}}, the categories for the county/district are sorted as "Isle of Wight". Similarly, for settlements such as
Isle of Wight, Virginia
, the prefix is not moved.
Hyphens, apostrophes and periods / full stops are the only punctuation marks that should be kept in sort values. The only exception is the apostrophe in names beginning with
, which should be removed. For example,
Eugene O'Neill
is sorted as
{{DEFAULTSORT:Oneill, Eugene}}
. All other punctuation marks (and punctuation-like diacritics) should be removed. Dashes can be replaced with hyphens. (Commas can be added when re-ordering words, as in the previous example, and other symbols can be added to the start to force the sort earlier, as explained above.)
Numbers will sort numerically (e.g. 9 sorts before 12), but some entries containing numbers need special sort keys to ensure proper numerical ordering. It is important to stick to the same system for all similar entries in a given category.
Separators (such as commas or periods) in numbers will interfere with numerical sorting so should be removed in sort keys. For example,
10,000 Maniacs
has the sort key
10000 Maniacs
Roman numerals
should be written as
modern numbers
in sort keys so that they sort numerically instead of alphabetically. For example, IX (9) comes before V (5) in alphabetical order, so
Pope John V
and
Pope John IX
should use the sort keys
John 5
and
John 9
, respectively.
Systematic sort keys are also used in other categories where the logical sort order is not alphabetical (for example, individual month articles in year categories such as
Category:2004
use sort keys like "*2004-04" for April). Again, such systems must be used consistently within a category.
In some categories, sort keys are used to exclude prefixes that are common to all or many of the entries, or are considered unimportant (such as "List of"). For example, in
Category:2004
the page
2004 in film
would have the sort key
Film
, and in
Category:2004 in Canada
the page
2004 Canadian federal budget
would have the sort key
Federal budget
Sort keys may be prefixed with
Greek letters
to place entries
after
the main alphabetical list. The following letters have special meaning by convention:
" (capital sigma) is used to place
stub
categories at the end of subcategory lists.
" (beta, displays as capital, "Β") is for
barnstars
" (capital delta) is for
documentation
, where sorting by Latin D is undesirable.
" (iota, displays as "Ι") is for
Wikipedia images
" (rho, displays as "Ρ") is for
portals
" (tau, displays as "Τ") is for
templates
. Keep in mind, template categories should not be added to content categories per
§ Templates
above.
" (upsilon, displays as "Υ") for
user templates
" (omega, displays as "Ω") is for
WikiProjects
Similar to the handling of Latin letters, if the sort key begins with a lowercase Greek letter, then the capital Greek letter will be displayed in headings on category pages. Several of these resemble Latin letters B, I, P, etc., but they will sort after Z.
Note:
Not all of these types are suitable for inclusion in
content categories
. For one-type categories, such as
template categories
, Greek letter grouping is not useful.
Sort keys are sometimes used even where they do not seem necessary – when they are the same as the page name, for example – in order to prevent other editors or automated tools from trying to infer a different default.
Inappropriate categorization
Shortcut
WP:BADCAT
WP:BADCAT
Anyone who can edit a page may remove a questionable categorization. If an article has an "incorrect" or "inappropriate" category, remove that category from the article, and replace it (if applicable) with a more correct category.
Even if an article may occupy the grey areas of a category's inclusion criteria, that is not a valid reason to keep the article in a category. If a particular article does not fit the inclusion criteria of a category,
then the article simply should not be added to it
If categorization of any particular page is
disputed
, please
discuss
the categorization on the
talk page
of the page in question. If the category seems reasonable, but questionable in some cases, consider whether you can solve (part of) the problem by writing a clearer
category description
If you have a proposal for a better name for the category or for a wider re-arrangement of the categorization scheme, or if you have a concern that may apply to several members of the category (such as if the category violates one or more sections on this page,
Wikipedia:Categorizing articles about people
Wikipedia:Overcategorization
, or other Wikipedia
policies and guidelines
), you can start or participate in a discussion about the category.
Category talk pages are not always widely
watched
. Consider whether you can
invite more potentially interested people
to take part in a discussion, such as by discussing it at a relevant
WikiProject
, or at
Wikipedia:WikiProject Categories
. Another option could be to nominate the category for discussion at
Wikipedia:Categories for discussion
, or if the
category name
has an obvious typographical error, you can list it for speedy renaming at
Wikipedia:Categories for discussion/Speedy
See
Wikipedia:Categories for discussion/How-to
for instructions on how to use the templates for:
deletion
{{
cfd
}}
),
renaming
{{
cfr
}}
), or
merging
{{
cfm
}}
).
If you are in a content dispute, see
Wikipedia:Dispute resolution
for what to do next.
Category cleanup templates
Article with insufficient categories:
{{
Improve categories
}}
indicates that the article needs additional or more specific categories. It is recommended that this template be placed at the
bottom
of the page, where readers will look for the categories.
Article with too many categories:
Use
{{
Recategorize
}}
when there are too many categories. Put this template
at the top
of articles.
Category unknown:
If you're not sure where to categorize a particular page, add the
{{
Uncategorized
}}
template to it, and other editors (such as those monitoring
Wikipedia:WikiProject Categories/uncategorized
) will help find appropriate categories for it.
See also
Wikipedia:Categorization dos and don'ts
(information page summarizing key points of this guideline)
Help:Category
Wikipedia:FAQ/Categories
Wikipedia:FAQ/Categorization
Wikipedia:Category names
Wikipedia:Categories, lists, and navigation templates
Wikipedia:Categorizing redirects
Wikipedia:Category suppression
Wikipedia:WikiProject Categories
m:Association of Categorist Wikipedians
Category:Wikipedia essays about categorization
For browsing
Wikipedia:PetScan
(formerly CatScan)
Wikipedia:Category classification templates
(category tree jumping)
Wikipedia:Category intersection
(ability to find articles that are in more than one category)
Special:Categories
(lists all existing categories alphabetically)
Special:CategoryTree
Category:Contents
Category:Wikipedia categories
For maintenance
Wikipedia:Maintenance
Wikipedia:Categories for discussion
Special:MostLinkedCategories
Special:UncategorizedFiles
Special:UncategorizedPages
Special:UnusedCategories
Special:WantedCategories
Wikipedia:Category combinatorics
Wikipedia:Database reports#Categories
Template:Category link with count
Template:Wikipedia categorization navbox
Wikipedia:HotCat
commons:Help:Gadget-Cat-a-lot
, script for moving subcategories between categories
Notes
Additionally, the top-level category,
Category:Contents
, has no parent category.
in declarative statements, rather than table or list form
For an attempt to fix this issue in
MediaWiki
see
T5311
Mathematically speaking, this means that the system approximates a
directed acyclic graph
This condition can be formulated in terms of
graph theory
as follows: the directed graph that has the categories as vertices and the parent–child relationships as edges should be
acyclic
i.e. in code,
{{DEFAULTSORT:Washington, George}}
In 2016, English Wikipedia's category collation was changed to "uca-default", which is based on the
Unicode collation algorithm
(UCA). The most noticeable difference is that UCA groups characters with diacritics with their non-diacritic versions. See
Wikipedia talk:Categorization/Archive 16 § OK to switch English Wikipedia's category collation to uca-default?
and
Wikipedia:Village pump (technical)/Archive 149 § Sorting in categories unreliable for a few days
Previously, zero padding was required to ensure single-digit numbers sorted before double-digit numbers (e.g. "09" for 9). This is no longer necessary.
"µ" (
mu
) was previously used, but the capital version "Μ" was confusing.
Wikipedia key
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(?)
Five pillars
Ignore all rules
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(?)
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(?)
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(?)
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