Commons talk:Categories

Intersection of subject and medium?

Do we need categories for narrow intersections of very specific topics and broad and largely unimportant media? e.g. Category:Black and white photographs of Haarlem Baseball Week

What does this add? What does it add that a trivial Petscan or SPARQL query can't do better? All it does is spread the navigation tree broader, making it more effort to both navigate and to maintain.

This is particularly the case for 'black and white photographs' where this is simply the default medium for many decades, then with a shift to colour film, then digital cameras, then phones. How far should we go with this?

@Waz8: @Denniscabrams: Andy Dingley (talk) 14:33, 27 July 2026 (UTC)

@Andy Dingley: Do we have simple, easy to follow instructions for making Petscan and SPARQL queries?   — 🇺🇦Jeff G. ツ please ping or talk to me🇺🇦 16:10, 27 July 2026 (UTC)

Of course not. Wikimedia is perennially obscure. Petscan is fairly easy for this, for anyone who knows how to do any basic querying of Commons with it. Andy Dingley (talk) 16:15, 27 July 2026 (UTC)

Then yes, we need such categories.   — 🇺🇦Jeff G. ツ please ping or talk to me🇺🇦 20:52, 27 July 2026 (UTC)

Why? And which ones? (i.e. how many categories are we going to duplicate like this?)

We have easy automatic ways to achieve the same result. Whether you've read the documentation and know how to do it is another matter. There is still the question of why such intersections need to be identified at all. Do they have any value? Andy Dingley (talk) 12:00, 28 July 2026 (UTC)

• This category is populated with 95 photos and looks fine to me. We don't strictly need such intersection categories, but they do no harm that I can see and some might find them useful. -- Infrogmation of New Orleans (talk) 12:23, 28 July 2026 (UTC)

So they don't add any value. Andy Dingley (talk) 18:50, 28 July 2026 (UTC)

• I believe the 'black and white photographs' categories are for any B&W/grayscale images regardless of their original medium rather than media which were originally made with B&W film, though this is probably the case for the vast majority of them. I've never encountered any category for an image's original medium, whether or not it's an intersection one. I've been a Commons editor for over 10 years, and I was not even aware of Petscan. (Thanks for the tip, though!) Therefore, I believe that the vast majority of Commons readers -- some of which have merely been directed to Commons by a Wikipedia link -- are not aware of it, either. Even if they were, IMHO, it's unrealistic to expect them to learn how to use it, when they just came here to browse. In addition, the Petscan Thumbnails view is not as "clean" as a Commons category, nor can one view the images in a slideshow as can be done within a category. So, at least for now, these intersection categories are needed. Waz8 (talk) 03:56, 3 August 2026 (UTC)

Bulk stripping categories, to leave no visible categories at all?

[1] and a whole bunch for File:Breda_(04.07.2026)_<nn>.jpg and similar files from Category:Breda.

Category:Breda is a broad and blunt category. But it's a real category and at least a start on useful categorization. Is it a reasonable edit to bulk remove it, leaving no visible cats at all? At the same time as we're trying to remove a legacy backlog of files in the same position: Commons:Village pump#How to categorize 45,000 media needing categories as of 2023?, why would we want to create even more of them? Andy Dingley (talk) 20:57, 16 August 2026 (UTC)

Pinging @Fantaglobe11 - Jmabel ! talk 00:21, 17 August 2026 (UTC)

This is due to inconsistencies between the "Photographs taken on" categories and their parent categories. It doesn’t make sorting any easier if you’re not allowed to sort according to the rules (Commons:Categories#Over-categorization) when the subcategory is hidden. Furthermore, users should be encouraged to categorise their photos sensibly, rather than dumping them. We have already discussed a similar issue in November 2025; see Commons:Village pump/Archive/2025/11#Moving photographs from a normal to a hidden category: Is this OK?. Best regards, Fantaglobe11 (talk) 16:03, 18 August 2026 (UTC)

We discussed a similar issue previously (I was unaware of this). There was no support for your view.

There are no 'inconsistencies' here. Andy Dingley (talk) 18:12, 18 August 2026 (UTC)

@Fantaglobe11: It doesn’t make sorting any easier if you’re not allowed to sort according to the rules (Commons:Categories#Over-categorization) when the subcategory is hidden. I don't know for sure what you are driving at, but non-topical (hidden) categories should not be used to diffuse topical categories. Non-topical categories are visible only to logged in users, and provide zero information to end users of Commons. (BTW, I see that the particular file singled out by Andy Dingley had now been better categorized.)- Jmabel ! talk 23:52, 18 August 2026 (UTC)

However, there are lots of them, especially all those "Country photographs taken on YYYY-MM-DD"... Could you please give me a specific rule that prohibits this? No such rule was mentioned to me during that discussion either. Thanks, Fantaglobe11 (talk) 17:23, 20 August 2026 (UTC)

• The question in this post is phrased as, "Bulk stripping categories, to leave no visible categories at all?"

I know of no specific policy regarding that (this is Commons, not en:Wikipedia, formally stated policies are few). That is why I phrased exactly this, and in the form of a question.

I would suggest that any policy should be based around this. Removing visible categories, leaving either none, only hidden categories (as happened here), or only purely maintenance categories, should be discouraged.

Certainly removing Category:Breda as the only visible category made the content effectively invisible to most users, and also to many of those who might then have gone on to improve the categorization. Fortunately Görkem Yavuz did go on to do this for us. Andy Dingley (talk) 18:12, 20 August 2026 (UTC)

Hi all. I was not included in the discussion since I was not pinged at the beginning, but what I would like to mention is that I do not think users should remove content from a main category without providing a sufficient reason.

In the case of my photographs, I do not always name the files specifically; rather, I tend to give them a general name. I have already uploaded almost 15,000 photos to Commons, and I have a broader vision that uploading my photos here contributes to the digital archiving of cities. I do not think we always need to provide very detailed descriptions or immediately place every photo into the most specific possible category.

In a way, this is a collaborative platform where everyone contributes from a different angle. Someone takes photographs and adds them to the main categories, while others can help classify them into more specific subcategories over time.

I did not intend to start an edit war, but I found the removal of the Breda, Netherlands category from my files quite baseless, especially since this made them unavailable to the public through that category. As long as the photographs were taken in Breda (or another city), I think they can remain in the parent category and gradually be distributed into more specific categories over time. This seems more logical and efficient than removing them from the relevant category altogether.

Wish you all good contributions! Görkem Yavuz (talk) 19:24, 20 August 2026 (UTC)

@Görkem Yavuz: I do not think we always need to provide very detailed descriptions or immediately place every photo into the most specific possible category. This is getting aside from the main topic at hand here, but you are dead opposite to the general understanding of the community here. While there are a small number of users who like doing categorization as such, and a slightly larger number who will willingly refine categorization of other people's photos in areas where their knowledge goes deeper than the uploaders (e.g. I will categorize photos taken by a tourist in a city I know well; some people are very good at refining precise species of insects; etc.), in general most of us consider this as drawing time away from working uploading our own content, or uploading third-party content that we specifically want to upload, or improving documentation on archival photos that may require proper research, etc., or work on a sister project that they consider their home wiki. Most of the time, no one can do a better job than you of describing and categorizing your own uploads, and when you fail to do so you are creating generally unwelcome work for others. Users have been blocked—or blocked from uploading—for doing just that for a large number of photos. - Jmabel ! talk 03:10, 21 August 2026 (UTC)

• I do not think we always need to provide very detailed descriptions or immediately place every photo into the most specific possible category.

Agreed. Although less so for filenames, as they're a bit harder to change afterwards.

We're an incremental project. Many of the medium-scale tasks (like a large upload batch) are just too big to take to completion in one go. Often we don't even know where they need to go either, we develop the destination (i.e. the category structure) as we go and as we learn more about the distribution of the content we're dealing with. Those of us who've dealt with >10k image photo libraries from one initial category will recognise this. Andy Dingley (talk) 10:01, 21 August 2026 (UTC),

@Andy Dingley: sure. I was thinking more of "own work". - Jmabel ! talk 18:51, 21 August 2026 (UTC)

• The discussion of overcategorization in this document probably needs to be more specific in saying that it is about topical categories; also that hidden categories are never substitutes for topical categories. - Jmabel ! talk 03:12, 21 August 2026 (UTC)

  I can well understand your points and agree with many of them. However, I would like to raise the following points:

  • @Andy Dingley: Oops, I see. It makes sense to discuss a rule like that. Generally speaking, I question the usefulness of hidden categories such as Country photographs taken on YYYY-MM-DD, given that most parent categories aren’t hidden (except for Photographs taken on YYYY-MM-DD, of course). However, that’s probably a discussion for another time.
  • Also, I understand that uploading a large number of photos involves a lot of work. However, in my opinion, you cannot expect others to do the work for you. Of course, categorising isn't for everyone, but as already suggested, the person uploading the photos is best placed to judge how their own work should be categorised.
  • I do not consider simply placing one’s own photos in a main category such as Breda to be a productive approach. Unfortunately, templates such as Categorize do not exist for no reason; rather, they are designed to prevent main categories from becoming overcrowded. In itself, it is not a bad idea to use such categories in order to distribute the photos further into the relevant subcategories. In the case of Rotterdam, this often works very well (the category is frequently empty of photos), but it requires active management. In my view, that is asking too much.
  • Naming files as Breda (04.07.2026) 01.jpg goes against our usual practice. It is precisely such examples that are cited as reasons for moving files in the Move menu (the example given there is File:Paris 319.jpg). In my opinion, such naming conventions should be avoided.

  Please feel free to share your thoughts on these points. Best regards, Fantaglobe11 (talk) 19:47, 21 August 2026 (UTC)

  • @Fantaglobe11: all of these latter points are fine, but they do not negate the issue we started with: if the pre-existing topical category was not actively wrong, and you are not refining it to a more precise topical category, just leave it alone. Feel free to add hidden categories, but not to use that as a basis to remove topical categories. - Jmabel ! talk 21:49, 21 August 2026 (UTC)

I think this could be well addressed just by changing "Also user categories are exempted of over-categorization" to (fixing grammar while I'm at it) "Also hidden categories, including user categories, are exempt from over-categorization". - Jmabel ! talk 23:21, 28 August 2026 (UTC)

red links to empty categories in section #Architectural structures

A lot of red links in section -> https://commons.wikimedia.org/wiki/Commons:Categories#Architectural_structures indicate the demonstrated categories are empty. At least one element should be present in thoses categories to illustrate the contents.Please fill them for the readers to have a coherent explaination. Thanks. --Christian 🇫🇷 FR (talk) 14:54, 28 August 2026 (UTC)

Weirder yet, this is not a matter of categories having been moved since this was written. These categories never existed. So basically, someone wrote up a policy recommending the use of nonexistent categories. - Jmabel ! talk 22:51, 28 August 2026 (UTC)

I believe Special:Diff/1268956245 should sufficiently address this. Sorry to cause yet another round of markup for translation. - Jmabel ! talk 23:18, 28 August 2026 (UTC)