Commons:Kategorye

1. How to find the appropriate categories

• Find categories with the search engine (see #Categorization tips)
• or check how similar files are categorized (some may not be categorized though)
• or start from the main topical category (Category:Topics)
• Starting from these categories, check their parent or sub-categories to find an appropriate category. Avoid picking too general categories.

2. Add the categories to the file

• Select them on the upload form
• or: add them manually by adding, e.g. [[Category:Foobar]] to the file description page (see #Categorizing pages)
• or: use HotCat (see Help:Gadget-HotCat)
• or: use Cat-a-lot (see Help:Gadget-Cat-a-lot)

The main principles are:

The category structure is (ideally) a multi-hierarchy with a single root category, Category:CommonsRoot. All categories (except CommonsRoot) should be contained in at least one other category. There should be no cycles (i.e. a category should not contain itself, directly or indirectly).

The page (file, category) should be put in the most specific category/categories that fit(s) the page (not directly to its parent categories). A category can have more parent categories. A category can combine two (or more) different criteria; such categories are called "compound categories" or "intersection categories". E.g. the root category Category:Churches and the root category Category:Russia have a common subcategory Churches in Russia.

This principle suggests not to combine too many different criteria.

We should not classify items which are related to different subjects in the same category. There should be one category per topic; multi-subject categories should be avoided. The category name should be unambiguous and not homonymous.

Identical items should have identical names for all countries and at all levels of categorization. The categorization structure should be as systematical and unified as possible, and local dialects and terminology should be suppressed in favour of universality if possible. Analogic categorization branches should have an analogic structure.

The category structure should reflect a hierarchy of concepts, from the most generic one down to the very specific. The structure uses and combines more types of relation, e. g.

• Hyponymy: a sort/kind/type of… (typically in biological taxonomy)
• Meronymy: a part of…, a member of… (typically for geographical division, building/room, device/component etc.)

• Attributes:
  • Qualitative and general attributes (color, shape, size, ability or disability, nationality, technique, quality, awards…)
  • Location: where, in…, from… (place/event, place/building, place/exhibit, place/people, country/language, source/work, factory or country/product etc.)
  • Timing: when (time/event, time/depicted situation, time of birth, inception or construction, time of death, demolition or termination etc.)

• Agentive and influence relations: (creator/work, device/product, company/product, discipline or profession/their subjects and terms, parent/children, subordination, owner/property, initiator/follower, subject/other subjects dedicated to it or named after it, subject/its duplicate, imitation, depiction or symbol etc etc.)
• Modification: original/modified or modified/original (avoid cyclic structure) – renamed, rebuilt, repurposed or transformed subjects.

The top-most categories (the ones contained directly in CommonsRoot) divide the category structure by the purpose of the contained categories:

• Category:Topics – This category is the global common root of the media files categorized by the TOPIC. ALL media files should be categorized under this category for the sake of allowing others to find them by topic. Topical categories shouldn't be included through templates.
• Category:Copyright statuses – This category is the global common root of the media files categorized by the 'LICENSE. ALL media files should be categorized under this category with the appropriate license tag. This type of category is added by including it in the templates.
• Category:Media by source – This category is the global common root of the media files categorized by the SOURCE, where they come from (books, collections, sites, etc.). This type of category is generally added by template.
• Category:Media types – This category is the global common root of the media files categorized by the Media TYPE. Please note that this type of categorization is sometimes omitted for images, since the vast majority of files on the Commons are images of some sort.

• Category:Commons – This category is the global common root of categorizing Commons maintenance tasks and pages (Commons:-, and Help:-) except for media files. The translated pages in each language should be categorized under their language categories, using the "Category:Commons-ISO-LANGUAGE-CODE" style. The structure of Category:Commons-en is the sample hierarchy for every other language sub category. Do not use two colons in category or page names. See this discussion and Help:Namespaces.

There is a sub category Category:Commons maintenance content, which is for the special maintenance of Wikimedia Commons global common contents and which does not get translated.　ALL media files should be categorized under the first 4 categories below, but ONLY files having problems and needing to be fixed should also be in the sub-category Category:Commons maintenance content.

• Category:User categories – this is for categories that contain Commons users' galleries, images and texts, sorted by things like the language they speak. This also contains the Category:User galleries, which is for user specific (i.e. non-topic) galleries that don't need to be in English language.

Categories grouping subcategories by name should generally be named "by name" rather than "by alphabet" (e.g. Category:Ships by name).

We still lack internationalization for category names, but this issue should be resolved with appropriate changes to the MediaWiki software (see T31928: Show translated titles per user language in categories too). Creating intermingled category structures in different languages would only make things worse.

For a general discussion of MediaWiki's category feature, see the manual page on categories.

To add a page (be it an image, a gallery page, or a category page) to a category, add the following code to the end of the page.

For example, if you are uploading a diagram showing the orbit of comets, you could add the following to the image description page:

This will make the diagram show up in the categories Astronomical diagrams and Comets.

For information on how to find good categories for your uploads and galleries, read the section Find an appropriate category below.

To create a new category:

1. Do a thorough search, to be sure there isn't an existing category that will serve the purpose.
2. Find images (or a gallery or other pages) which should be put in the new category. Edit this page, and at the end insert the new category reference. e.g. [[Category:Title]]. Save the edited page. The new category appears as a red link at the bottom of the page.
3. Click on that red link. The new, empty, category page appears for editing. You can now edit the category like any other wiki page.

A category page should contain the following information (in order of importance):

• Category-links that put it into one or more parent categories. At the bottom of the new page, insert lines of the form [[Category:Relevant categories]].
• A short description text that explains what should be in the category, if the title is not clear or unambiguous enough on its own. Descriptions in particular languages can be tagged e.g. with the template {{ab|...}} for description in Abkhazian, {{en|...}} for description in English, etc., as listed in Commons:Language templates); or using the {{Multilingual description}} template to show only the description in the user’s preferred language if there is one.

• Interwiki or interlanguage links to the article or category with the same topic in Wikipedia by adding the appropriate sitelinks on the corresponding Wikidata page. After creating the category page, click "Add links" under "In Wikipedia" on the bottom of the sidebar to the left to add them.

See also #How to categorize: guidance by topic for guidance on specific classes of category, e.g. categories about #People.

If a category should be sorted according to a different string than the category title, there are two ways:

Defining a sortkey (sort string) for all parent categories:

Defining a sortkey only for one of the parent categories:

The default sort order on Commons is:

→See also: Meta:Help:Sorting#Sort modes for more information.

Please see Commons:Rename a category.

Pages (including category pages) are categorized according to their subject, and not to their contents, because the contents are generally not a permanent feature of the category page; in particular, you can momentarily find inappropriate contents in a category page.

Example: Assume that Category:Spheres contains only pictures of crystal balls. You must not add Category:Glass in the category page, according to the current contents, because you can have spheres made with a great variety of materials. Normally, any picture showing a glass object would be already categorized in Category:Glass (or in a category of its substructure). So, if the Category:Spheres is really crowded with crystal balls pictures, it would be a better idea to create a new category page, like Category:Glass spheres or Category:Crystal balls, categorized in Category:Spheres and Category:Glass.

Generally files should only be in the most specific category that exists for certain topic. For example files in Category:Looking up the center of the Eiffel Tower should not also be in Category:Paris (see over-categorization below). If you do not find a category that fits your purpose, you can create it — but carefully read the section about using categories first.

This does not mean that an image only belongs in one category; it just means that images should not be in redundant or non-specific categories. For instance, an image of a Polar Bear being rescued from an iceberg by a helicopter should be in Category:Ursus maritimus, Category:Icebergs and Category:Rescue helicopters. It should not, however, be in Category:Ursidae, Category:Sea ice or Category:Aircraft.

To find appropriate categories for your uploads, you should navigate the category structure starting from a generic category. Narrow your search down to subcategories until you find the most specific category that fits the file you uploaded. You can navigate the category structure by following links to subcategories, or expanding the tree of subcategories by clicking on the little ▶ symbols on subcategory names. The Major categories section above provides a starting point, and the How to categorize: guidance by topic covers some topics more.

A file that depicts only one relevant subject should not be over-categorized. Where a file depicts additional relevant subjects, and the additional subjects do not have their own subcategories, consideration can be given to temporarily categorizing the image in both the subcategory and the parent category.

For example, this situation might arise in the case of a photograph of three politicians, one of whom is Angela Merkel (who has her own Commons category), with two other politicians who do not yet have their own categories. While the image would undoubtedly be categorized in Category:Angela Merkel or one of its subcategories, it would typically be considered to be over-categorization to also include it in Category:Politicians of Germany. Users would, however, be unlikely to search for the two other politicians in the Merkel category. Ideally, we would create specific subcategories for the two other politicians (where warranted), or find other relevant subcategories (e.g. Category:Politicians of Bavaria or Category:Members of the FDP, etc.), that would enable us to avoid over-categorization. In some circumstances, however, we may need to temporarily categorize the image in Category:Politicians of Germany where other appropriate subcategories do not yet exist.

Countries may be categorized as part of multiple overlapping categories. For example, Category:India is in Category:Countries of South Asia as well as Category:Countries of Asia.

Also user categories are exempted of over-categorization as those are not visible to most viewers, and project users include them for many different purposes like sorting, stats, filling values for userboxes, etc.

For some categories, there is special guidance on how best to sort content within that category. This guidance can be found in a category scheme or a Commons project for your topic. There is also some categorizing information in this section and sometimes there is guidance at the top of the category's page, in the Category namespace. So, for instance, some guidance on categorizing content depicting people is at the top of Category:People, and some is in the section People below.

Content depicting Structures, e.g. Buildings and Tunnels, can be classified like this:

Structure Category. First check if there is already a Category for this specific structure.

• If yes: put it in there.
• If no: If you have more than two pictures: create a new Category, named after the structure. For example Category:Rheinbrücke Emmerich. Use the common name, not necessarily the English one.

Then you categorize the category (NOT each single picture!) under the following possibilities:

• Location: see Category:Structures by country, for example: Category:Structures in Germany
• Function: see Category:Structures by function, for example: Category:Bridges
• Type / construction: see Category:Structures by type
• Material: see Category:Structures by material for example Category:Concrete structures
• Engineer: see Category:Structural engineers for example: Category:John A. Roebling
• Architect: see Category:Architects for example: Category:Norman Foster

Afterwards, categorize the image by the way the structure is depicted, such as:

• Painting or drawing: see Category:Paintings of structures or Category:Drawings of structures
• Postcard: see Category:Postcards of structures
• By view or point of view, see Category:Structures by view, with subcategories such as Category:Structures viewed from above, etc.

Also consider the part and the context visible:

• For parts, see categories such as Category:Bridge elements, Category:Tunnel portals, Category:Interiors of towers
• For context, see categories such as Category:People with structures, Category:Trains on bridges

Content depicting people should be put in categories which describe them, such as Category:Economists from the United States. Start exploring at Category:People.

Please see Commons:Suggested category scheme for people for details on how to name and organize these categories.

Content depicting a given subject from a common vantage point are grouped in Views of Subject from Viewpoint categories such as Views of Cathedral of Seville from the Giralda. Such categories should be subcategories of both the subject's category (Cathedral of Seville in this example) and the viewpoint's category (Giralda in this example).

In this example, the Views of Cathedral of Seville from the Giralda category is not placed directly in the subject and viewpoint categories, but in Views of the Cathedral of Seville and Views from Giralda. Such intermediate categories are often necessary to create structure and avoid over-categorization, particularly for views of a city from a vantage point located within the city. For example, Views of Rome from the Pincio needs the intermediate category Views of Rome to avoid placing it directly in Rome, which would constitute over-categorization.

Texts, such as scans of books, should normally have a category for each version of the scan and each edition of the text. Thus a book published in three separate editions would have a parent category for the book, three subcategories for each text, and further subcategories for the text as a jpeg, a DjVu, etc., assuming each version had actually been uploaded. (Categories would not be created for editions not held on Commons.) This is particularly important for files in formats other than DjVu and PDF, where the category is the only practical means of keeping the scans together; see eg. Category:The Chronicles of England, Scotland and Ireland, Holinshed, 1587 which contains 2857 jpeg images of page scans.

For categorization issues related to mass content donations from GLAMs (Galleries, Libraries, Archives & Museums), please see Commons:Guide to batch uploading#Categories.

Currently, a bot checks if newly uploaded files are categorized in topical categories and attempts to categorize files that are not. Before 17 June 2015, CategorizationBot was responsible for this job. As of June 2019, SteinsplitterBot occasionally checks for uncategorized files. The workflow is the following:

1. User uploads a new file and adds categories (or not).
2. A bot checks if the file is categorized.
   • File is already categorized => ok
   • File is not categorized => the bot tags the file for Category:Media needing categories. Today's files are in Category:Media needing categories as of 19 December 2024
3. Users categorize files further (e.g. category diffusion below)

See also: User:CategorizationBot#Process, categorization statistics

Other, if manual, categorization workflows are possible :

• Category filling: Use appropriate keywords in the search engine to find the files that should be in a given category, and put them there.
• Category diffusing: Go to Category:Categories requiring diffusion, select a crowded category, create appropriate subcategories if needed, and move the files to the subcategories. Gadgets like Cat-a-lot and HotCat can help.

Many non-topical categories are marked with the magic word __HIDDENCAT__ or {{Hiddencat}} on the category page. The advantage of using the template is that there will be an additional Infobox for the user stating that:

"This category is not shown on its member pages unless the appropriate user preference is set." 

An example of using __HIDDENCAT__ is Category:PD NASA. An example of using the template is Category:Wildtunis/100WikiCommonsDays.

While categories are generally visible on every page, categories marked with __HIDDENCAT__ or {{Hiddencat}} are only visible:

• on the edit screen: at the end of the screen, below the edit box
• on category pages:
  • on subcategories to the hidden category: in the normal location, but on a separate line with a smaller typeface and the label "Hidden categories."
  • on parent categories: in the same way as other categories
• on file description pages and gallery pages: for logged-in users who have selected to "Show hidden categories" in their appearance preferences. This is activated for all newly registered users.

This feature is generally used for template-based categories, such as license tag based categories. For example, placing {{PD-old-100}} on a file description page adds the file to Category:Author died more than 100 years ago public domain images, which is marked with __HIDDENCAT__.

For more details, see the help section on hidden categories for Mediawiki (the software that Commons uses).

Some templates are designed for use on category pages - see Category:Category namespace templates. If the category is linked to a Wikidata entry, then you can use:

• {{Wikidata Infobox}}

which displays a summary of the topic's information that is available on Wikidata, and also auto-adds birth/death/name/monument ID categories.

Some of the more commonly used ones are Category:Category header templates such as:

• {{Category TOC}} and {{LargeCategoryTOC}} - to provide a table of contents for very large categories with many subcategories
• {{ImageTOC}} and {{FileCategoryTOC}} - to provide a table of contents for large categories with many files and few subcategories
• {{Image template notice}} and {{Autocat}} - for maintenance categories populated by a specific template.
• {{Global maintenance category}} and {{Local maintenance category}}

• {{MetaCat}} - for categories which should only contain other categories
  • {{By country category}}, {{By language category}}, {{By century category}} - for specific types of meta category
• {{CatDiffuse}} (temporary) and {{Categorise}} (permanent) - for large categories which need maintenance to move files into subcategories
• {{Category tree}}

• Gadgets enabled through the user preferences
  • Cat-a-lot: A tool that helps with moving multiple files between categories or adding categories to search results. [documentation / talk] 
  • HotCat: ^d Easily add / remove / change a category on a page, with name suggestions. [documentation / example / talk] 
  • Gallery Details: Adds a link in the toolbox to display galleries and categories (and Newimages and Search result pages) with extensive details from file description pages and links to easily mark an image without source, etc. If Pretty log is activated, it also works on Log pages. [documentation / talk] 
  • Place categories above content, but below image on file description pages.  Modifies the placement of categories on the user interface.
  • Add a link to category pages to search for the category name with the option "-incategory". This excludes files already in the category (doesn't work if the category was added by a template). [talk] 

• Toollabs / toolserver tools
  • PetScan – this new version has other features
  • English vCat – plots categories trees. For example https://tools.wmflabs.org/vcat/render?wiki=commonswiki&category=Water%20wells generates graph for parent categories of Category:Water wells

• Special pages
  • Alphabetic lists of categories with files or other pages in them – including nonexistent categories
  • Category tree
  • Unused categories – including categories redirected with {{Category redirect}}
  • Uncategorized categories

• Bookmarklets
  • Category redirect bookmarklets
  • Bookmarklets for categorization of aircraft by registration
• Scripts, software, etc.
  • AutoWikiBrowser (for access: checkpage)
  • pywikipediabot category.py (for access: request page)
  • Degrandparent – a tool to remove files from a category if they are also in one or more of its subcategories.

• Bots
  • SieBot – renames or adds categories. See documentation – requests.
  • EuseBot – adds additional parent categories to categories (and galleries) depending on which category an article in English Wikipedia is in. For requests.
  • RussBot – clears Non-empty category redirects
  • CategorizationBot – adds uncategorized images into Media needing categories – notifies uploaders, and attempts to categorize images (Media needing category review)
  • Requests for work to be done