I just looked on SO, and found that there are about 12,880 tags with only a single use. There are 26,250 used less than 10 times.

That's just too many for the community to fix. I think we need some automatic cleanup here.

I suggest you add a cleanup process to remove all tags used less than a certain number of times more than a month after their creation. That would give a legitimate tag a while to become used more, while removing those that will never be used more than a few times.

Edit: Here are the tags from page 512. I've highlighted the ones I think are most likely bad tags. I even fixed a few:

  • installer-class
  • inspector
  • installation-tools
  • insert-worksheet
  • insets
  • insomnia-mysteries
  • inorder
  • inprivate
  • inprocfactory
  • inprocserver
  • in-progress
  • input-button
  • input-buffer
  • input-mask
  • inputformsection
  • insert-nested-select
  • insert-parameters
  • insert-img-to-option
  • insert-data
  • insertdate
  • insert-delayed
  • insertafter
  • insertchildbefore
  • input-mode
  • input-simulation
  • inputpanel
  • inputrc
  • input-redirection
  • inquiry-management
  • inputstreamreader
  • input-string
  • input-testing
  • infocards
  • infochannel
  • infogrid
  • inflector
  • influence
  • info-plist
  • inforeader
  • inform
  • inform7
  • information-base
  • information-card
  • information-dispersal
  • informed-search
  • information-sources
  • information-technology
  • information-ownership
  • information-science
  • info-vis
  • informx (fixed now)
  • info-window
  • infralution
  • inheritence (typo - fixed)
  • initialcapacity
  • initial-context
  • initialization-block
  • initfileurlwithpath
  • inline-comments
  • inline-cpp
  • inline-edit
  • inlinec
  • initialize-request-handl
  • injectable
  • injectors
  • init-script
  • inittab
  • initwithcontentsoffile
  • initwithcontentsofurl
  • inlinks
  • 1
    However, those tags may be needed again...I suggest only cleaning up the really uncommon tags...but then again, you never know.
    – studiohack
    Commented Apr 30, 2010 at 17:58
  • 1
    John - How many tags are there in total?
    – user27414
    Commented Apr 30, 2010 at 19:32
  • 1
    @studiohack: I meant the single-use tags, if they're still single-use a month after their creation. If they're needed again, they can be created again. Commented May 1, 2010 at 1:10
  • 6
    @Jon: as of this moment, there aer 35,840 tags on SO. That means 36% of all tags are only used once. 73% of all tags are used fewer than 10 times. Now, we should also take age into account, but these are numbers that concern me. Commented May 1, 2010 at 1:13
  • @John S: oh ok. makes a lot more sense. +1
    – studiohack
    Commented May 1, 2010 at 2:21
  • @John - that's a lot more serious than I had thought. Ouch!
    – user27414
    Commented May 1, 2010 at 3:45
  • 17
    We can't get rid of [insomnia-mysteries]!!!
    – Earlz
    Commented May 17, 2010 at 18:31
  • 11
    What happens if a tag is deleted, and the question only has that one tag? Can there be questions with 0 tags?
    – Corey
    Commented May 18, 2010 at 8:20

16 Answers 16


I don't know -- can anyone make a case for these single use tags existing for more than a month?

edit: I am convinced this is a useful cleanup task, to remove these orphaned tags from the system automatically. I've implemented a routine that removes tags created more than 6 months ago (12 months on Meta sites) which have been used only a single time. It will run monthly.

Right now I am running it by hand over the tiers and I got these stats so far:

(note: where you see multiple posts being updated, it's because there are "extra" deleted posts with that tag.)

I spot checked a whole bunch of them, and removal seemed correct to me in every instance. It's almost always a case of over-tagging, where the question asker sprayed 1 or 2 "extra" tags on the question of extremely low value, when the more general tags they also included were perfectly adequate.

There is some code at the end to deal with questions which end up with ZERO tags after removal of the one-use orphan tags -- it tags these . But that is exceedingly rare.

Any tags not currently in use, or that happen to get orphaned through unusual means (rollback, merge, etc), are removed every 24 hours by a background process.

  • 22
    Surely there are technologies that are either too new or too rare to be used more than once in the first month.
    – user27414
    Commented Apr 30, 2010 at 17:07
  • 8
    @Jon B: If they are too rare, the tag isn't really that helpful, and people probably aren't seeking it out much, anyhow. If they are too new, the tag will be recreated later with more success once the technology becomes more popular (which means a small number of questions might improperly lose their tags, but this is OK imo). Killing a tag does not imply it will never exist again. That said, this number could be upped to 3 months (which is a LONG time), if you're paranoid about the time it takes.
    – Brian
    Commented Apr 30, 2010 at 19:19
  • 3
    @Brian - 3 months might be a little safer. Once the initial cleanup is done, I doubt the problem will get out of hand in a 3 month period.
    – user27414
    Commented Apr 30, 2010 at 19:34
  • 2
    @Jon: I don't have access to the data dump right now, or I'd do some more analysis of these tags. In particular, I think the time since their creation might be interesting as well. For instance, what percentage of the single-use tags are over six months old? Commented May 1, 2010 at 1:15
  • 2
    @Brian: Why would it be okay to have a presumably reasonable tag removed from a question that it is appropriate for? If I add a Blorgle tag to a question, and it fits that question, and it times out after three months, then another question is added that has the Blorgle tag...but now the first question doesn't? Why not? The tag is now considered "okay" again for the time being.
    – beska
    Commented May 18, 2010 at 15:25
  • 3
    @Jeff: I'll grant a lot of these single use tags are useless and silly...but to globally delete low use (but useful) tags because of a non-critical-mass userbase is to pretty much ensure that you'll never reach that critical mass userbase...you have to have these questions around with reasonable tags so they'll show up on search engines, so that those people know they can come to the SO site for their questions.
    – beska
    Commented May 18, 2010 at 15:28
  • 4
    @beska: Because perfect is the enemy of good. The benefits of zapping extraneous tags outweighs this.
    – Brian
    Commented May 24, 2010 at 21:45
  • Loving the (temporarily?) new rubik tag ;-)
    – Arjan
    Commented May 30, 2010 at 22:14
  • @arjan yeah that was the 1 in 20 where a rare tag was actually justified. Commented May 30, 2010 at 22:47
  • 8
    What if the [untagged] tag has only 1 question in 6 months? Will it also get deleted? Commented Jun 4, 2010 at 19:50
  • 1
    Wow, this is truly sad, now I have to go back and add in tags that haven't got a population here yet. We need people to be able to google these tags, so that they come here and we can build the population. Commented Jun 30, 2010 at 18:28
  • 1
    I've just had a look at Unix's single use tags. Some are useless and need culling (e.g. myths). Many others are legitimate (many are names of applications that get little traffic, e.g. mutt, nano), enough that I fear the automatic removal will do more harm than good. Commented Feb 18, 2011 at 0:17
  • 1
    @Jeff: There are two untagged questions from the early days of the site a little over 6 months ago, so I guess the script has run once already. I wouldn't be surprised to see quite a few legitimate tags see no activity in 6 months. The biggest problem is the questions that have multiple tags, one of which is something like a rare unix variant or rare application: we'll have no warning that the question has become hard to find. Commented Feb 18, 2011 at 0:46
  • 9
    @gilles if it's that rare it should be in the title or body and findable via search.. not everything HAS to be a tag Commented Feb 18, 2011 at 0:53
  • 6
    Just my 2 cents worth, but it seems as if a low use tag with a "follower" would be "more valid" as someone is interested and has taken the time to denote that they are, even if the tag has low use. Commented Aug 18, 2011 at 12:59

I really dislike the idea of automatically deleting perfectly legitimate tags just because they are not used frequently. If someone tags a question about the "xyzzy" programming language with the tag "xyzzy", then it seems rude to delete it even if there are only a couple of instances. You would basically be telling people with questions about rare or unusual technologies not to bother to come here.

  • 3
    Agreed. As I said in my answer, most of the low-occurrence tags I've seen have been used properly. I think the issue is more of removing the "garbage" tags -- misspellings, aliases of other tags which already exist, etc.
    – Jon Seigel
    Commented May 17, 2010 at 18:17
  • 2
    Well, in reality, obscure technologies are obscure and SO wouldn't be much help I don't think. I use some rare/obscure technology, and there are 0 tagged questions in that area. SO is very much a non-niche community. Commented May 17, 2010 at 18:22
  • I think we're to the point where a one time fix is justified, if it's combined with Stephen Steel's answer where something is put in place to make it easier to use existing tags vs creating new ones in the future. Commented May 17, 2010 at 18:25
  • 1
    @Joel: I really wish it was easier to get data on when tags were created. I would be very curious to see how many tags with 1 occurrence are >= 1 year old.
    – Jon Seigel
    Commented May 17, 2010 at 18:29
  • 3
    Obviously popular technologies are going to see the most traffic here but I do not get the feeling that the intent of the community was to exclude any technology from consideration. The proposal to delete tags just because they are uncommon seems at odds with the tagging concept. Commented May 17, 2010 at 18:29
  • @Chris - No one is talking about deleting any questions. The questions would still remain. And if this is the only tag associated with a question, than either we have to also keep the tag or the script will have to use a special tag - something like "obscure". That could even be a benefit for these questions, as I can imagine a lot of people would want to browse the obscure tag. Commented May 18, 2010 at 13:26
  • @Jon - you can't know exactly when a tag was first created, but you can use the datadump to find the oldest question that still has a given tag. Commented May 18, 2010 at 13:28
  • @Christopher - You must remember that infrequenly used tags carry considerable cost: they dilute the useful tags. The reason it is constantly necessary to merge tags for synonyms is that nobody bothers to look throgh 500 pages of existing tags to select appropriate ones - they just enter whatever occurs to them. Commented May 18, 2010 at 14:19
  • 5
    How do infrequent tags "dilute" useful ones? I can see how infrequent tags that refer to the same concept as a popular tag are bad, but no one has yet explained how an infrequent but unique tag presents any problem that could not be solved by better tag navigating UIs. Commented May 18, 2010 at 14:42
  • Xyzzy...how appropriate for me! My tags on this list are "inform7"...
    – beska
    Commented May 18, 2010 at 15:07
  • @Christopher - Some of the low use tags are good: if my question concerns the little used xyz programming language, then tagging it with "xyz" is appropriate. Then the small number of SO users familar with xyz might notice it. But many of the low use tags are not so useful. Many of these questions are not so unique that they really need to introduce new tags. While a better navigation UI might make it easier to wade through 500 pages of tags, but it will still take far more effort than most questioners are willing to expend. Commented May 18, 2010 at 20:52
  • 2
    This is in essence a question of scalability. In the long run for SO to remain successful it is going to have to solve the problem of having large number of tags. Crude automated tag deletion rules aren't going to solve that problem. It is actually pretty clear that the existing tagging scheme is overly simplistic and does not scale well. Commented May 19, 2010 at 13:22

I think the problem is likely to continue to get worse, as it arises from a simple fact: it is MUCH easier to introduce a new tag than it is to find existing ones that are suitable. Worse, the asymmetry in effort becomes more and more pronounced as the growing number of low use tags dilute the good ones. The frequent need to merge tags that are straightforward aliases of each other is proof of this (vs2010/visual-studio-2010, subversion/svn, mercurial/hg, etc.)

Ideally, it would be best if it required more effort on the part of the user to introduce a new tag than it takes to select ones that already exists.


Before you go arbitrarily removing tags, ask yourself "why?" What are you gaining?

It's not as if you are trimming down the tags list to a manageable size. People don't browse tags like a book. Tags are a valuable data-mining tool. Not a popularity contest. You're removing valid tags; possibly on rare, niche topics... arbitrarily, with little-to-no benefit.

The next time I am looking for a question about Infralution, I'd like to think the original authors question would be found. Not orphaned because the tag didn't meet the minimum-popularity quota.

  • you have to look at the data, though. This is like posts of 30k length. Are they valid? Perhaps. But the data shows us that the VAST VAST majority of 30k length posts are absolute garbage. Commented May 18, 2010 at 1:20
  • 5
    @Jeff Atwood - The OP's list of most likely invalid tags shows more than a third are valid. So the VAST VAST majority criteria may not apply. Either or -- my point was philosophical. Nothing I think will make a lick of difference to the system either way. Commented May 18, 2010 at 1:39
  • 5
    instances of 1 "valid" tags can also mean people are tagging at too low/granular a level. If I tag this discussion as "robert-jeff-may17", it's a theoertically valid tag, but not a useful one. Commented May 18, 2010 at 3:05
  • 2
    Robert, you could help by saying which of the tags in my list are valid, and why. Commented May 18, 2010 at 5:10
  • @John Saunders - I went by your statement "I've highlighted the ones I think are most likely bad tags." Commented May 18, 2010 at 14:33
  • @Jeff - "...can also mean" true. So let me ask you a different way. From hereon in, if someone see a post (older than a month) and one of the tags is only used once, delete it? Automatically? Commented May 18, 2010 at 14:46
  • @Robert: when I said "are most likely bad tags", I meant, "appear to have the highest probability, based on my areas of knowledge, of being bad tags". My areas of knowledge do not include a lot of things that are discussed on SO (PHP, Python, etc.), so I left unbolded the set of tags that I thought might possibly be valid. Note also that the tag list is an edit - the original question did not include a tag list. Commented May 19, 2010 at 2:03
  • I think a neat solution would be that any 'tagless' questions resulting from this clean-up should be tagged with the 'untagged' tag (if that makes sense). This would make a clean-up after the clean-up much easier.
    – Benjol
    Commented May 19, 2010 at 8:18

Okay...I am the "perpetrator" of one of these tags. Currently, my tag, "inform7" has only two questions, and I've asked both of them.

However, I've gotten good, quick answers for both of my questions, and neither question was voted down, so presumably both questions are at least semi-reasonable. Given that, my question is: if my tag is removed, what should I have tagged them with? Nothing else is very appropriate, and I think my tag actually is pretty spot on. Assuming we want more people to start using the site, and get a critical mass of this (admittedly niche) userbase, shouldn't the tag remain?

I'm all for tag consolidation, but auto-removing low use tags seems to be a bad solution (and, to be honest, if we're not talking about duplicate or joke tags, I'm not clear on what the "problem" is.)

  • No one is talking about banning these tags or other new tags. We're talking about a one-time cleanup that has the unfortunate side-effect of also catching some good existing tags, and pairing this with a new tag workflow that puts more emphasis on re-using existing tags to help avoid the need to repeat this in the future. Commented May 18, 2010 at 15:49
  • 5
    So we are talking about doing a brainless simple operation that isn't actually correct because we are too lazy to do the right thing? Commented May 18, 2010 at 16:27
  • 1
    @Joel: I understand the idea...but I'm wondering how much will be lost. Your point about adding a new workflow is critical...without that, I don't think there's a point...but with it, I can see the utility. Sending messages out to originators of affected questions would also be a good thing...I, for one, would be happy to follow a more rigorous workflow to recreate the (hopefully useful) tag so that the question wouldn't essentially be permenantly "tag-orphaned".
    – beska
    Commented May 18, 2010 at 16:53
  • 1
    @Joel: Also, while you say "we're talking about a one-time cleanup", I don't think that's what everyone is talking about. It seems as though people are suggesting things like an ongoing process which auto removes tags that haven't been used for a month, which is the idea that I'm more fervently against.
    – beska
    Commented May 18, 2010 at 17:00

I think automatically zapping tags is too heavy handed. There will be legit tags that squashed as a result, and some posts may end up with no tags at all (which could be a serious problem, depending on how the queries work).

I agree, though, that we have a problem here. Perhaps there is a way for tags to be queued up for mods or 10K users to review. In this manner they could be cleaned up slowly over time.

  • Obviously, if zapping the tag would result in questions without any tags, then the tag should not be zapped. Other than that, I say zap away!
    – nb69307
    Commented Apr 30, 2010 at 17:06
  • 1
    Any automated tool would have to look to see if a post has only one tag, as the Tag Merge/Remove tool does now. It won't let us remove a tag if any post would be left tagless as a result. Commented Apr 30, 2010 at 17:07
  • A merge is different, since the post will go from one tag to a different tag.
    – user27414
    Commented Apr 30, 2010 at 17:08
  • 1
    The same tool can be used to remove tags. Commented Apr 30, 2010 at 17:10
  • Still, I agree, I think slowly over time we can clean this up. Surely we're not creating tags faster than we can remove them, are we? Commented Apr 30, 2010 at 17:13
  • 1
    @Bill At the moment, I suspect we are!
    – nb69307
    Commented Apr 30, 2010 at 17:15

I started going through the single-use tags manually periodically, but the tags list on SO is over 500 pages long and growing fast, so it takes a while to go backwards in the tags to get to the 2-usage ones.

Certainly, there are a lot of single-use tags, but what I've found is that the vast majority of them are used properly. It would definitely help if I had 10k tools on SO to audit new tags...

In any event, with regards to an automated system, I don't think any such thing could work very well, as it's really a human problem. The context of the tag needs to be observed to determine whether or not it should exist. Enhancement of the 10k tools might be a better option (although I can't really suggest anything because I haven't used them before).

Once tag synonyms are implemented, it's tough to say if that will reduce or exacerbate the problem, but certainly there will be fewer tags overall in the system, which should help.


New technologies come out all the time, and it will take a while for their population to be big enough to get multiple questions on StackOverflow, but I'm sure we'd like the questions to be there one day. If someone asks a question for a specific technology early on, then he might get very little response, like here, but it would be a shame for the tag that categorizes that question to be removed. It will also cause duplicate questions to be asked eventually, since the logical tag for that type of question isn't attached for it.

While base-db is just getting started as a concept, I've also created a tag pi-db for OSIsoft's PI database that has a huge userbase all over the world, but the community here just hasn't been built yet.

I don't think we should aim StackOverflow to just the hot topics, we should be seeking to attract all programming communities, to make this THE preeminent place to ask programming questions. (Note this is biased from my own laziness, since I want to only have to go to one site to find all my answers).

  • No one is talking about banning these tags or other new tags. We're talking about a one-time cleanup that has the unfortunate side-effect of also catching some good existing tags, and pairing this with a new tag workflow that puts more emphasis on re-using existing tags to help avoid the need to repeat this in the future. Also, I think questions where the single-use tag is the only tag would of necessity be left alone. Commented May 18, 2010 at 16:45

This engine is all about promoting democratic processes, right? Why not allow voting on the tags themselves?

You get bonus rep for accepted tags, you lose rep for rejected tags. If tags are considered meaningful data, then they should be treated like all other meaningful data.

  • 1
    I like this idea conceptually...but I wonder if it would be just too much information/work for people to worry about. Implementation might be difficult. Still, the general concept seems good.
    – beska
    Commented May 18, 2010 at 16:56

I added a tag racket with only one question because the PLT-Scheme project are changing their name to Racket (currently offline). This was at the request of a user who wanted to add the tag themselves but could not because they didn't have enough reputation at the time. If the tag is removed then the same problem will happen again the next time someone tries to ask a Racket question. Removing rarely used tags every time it hits 1 usage will make it unlikely that it will ever be possible to use them. In this case an alternative would be to make plt-scheme a synonym for racket.

Another tag I created with only one question is android-send-me-logs for the project android-send-me-logs. Again the user that asked the question would not have had sufficient reputation to create this tag themselves.

Your proposal will result in the removal of these two tags, plus I'm sure many other tags in a similar position. Will this benefit the site? And will leaving these tags cause any harm?

  • The proposal will only get rid of these tags if they remain with only a small number of uses. Commented May 30, 2010 at 18:04
  • yes, they'd have to stay that way for 6 months under the current ruleset. Commented May 30, 2010 at 20:37

Coming to the party late, I have a minor concern.

Some people don't include the name of the technology they are using in the questions, assuming that putting it in the tag is sufficient.

Some of the untagged questions are going to degenerate into meaninglessness if you remove their tags.

Would it be possible to automatically modify the question text to append say "[Tag removed: xxyzy]"?


Here is an argument against zapping low-occurrence tags - they might be needed to meet site standards, or to convey important context for the question.

As an example, on Arqade, there is a de facto standard that each question should carry a tag identifying the game being asked about. In some cases, posters omit to identify the game in the title and/or body of the question, assuming that the tag is sufficient. (Sometimes this is intentional for entertainment value, if the question sounds particularly bizarre out of context, as in the currently top-voted question How can I tell if a corpse is safe to eat?)

But if there are very few questions about a particular game, the corresponding tag might have very low occurrence. For instance, there seems to be only one question about the game Pocket Harvest: How do I improve the rating of my crops?, and so the tag pocket-harvest has only one occurrence. If this tag were zapped, the question would be out of compliance with the "tag identifying the game" rule; worse, since the game's name is not mentioned in either the title or body, the question itself would become incomprehensible.

There are other sites with similar practices:

In these cases, the fact that a tag has low occurrence does not necessarily suggest that it is likely to be incorrect, nor that it can be safely removed - merely that it asks about something relatively obscure. (It should also be kept in mind that many SE sites have dramatically lower traffic than SO, so something that is "relatively obscure" for that site may actually be quite well known in absolute terms, like russia.)

In conclusion, at least for such sites, no, we should not zap the low-occurrence tags.

  • 1
    What does this have to do with the question? Commented Jul 23, 2015 at 1:48
  • 2
    Questions written this way are often harder to read anyway. But in almost all cases, a question that puts its information solely in tags does so precisely because that tag is relatively common in the site domain, and therefore logically should have lots of questions to prevent it from getting clobbered. Failing that, well, usually the revisions list will do the job for you. Commented Jul 23, 2015 at 1:55
  • @John: The question asks whether we should zap low-occurence tags. My answer is an argument that we should not, or if we do, then we should consider how to mitigate the issue I mention. Commented Jul 23, 2015 at 2:55
  • The question is about removing low-occurrence tags. The fact that they have few occurrences is taken as a proxy for the fact that many of these are incorrect. Are the tags you refer to incorrect? Do they have few occurrences? Commented Jul 23, 2015 at 3:05
  • @JohnSaunders: The tags in question are typically not incorrect but may have few occurences. For example, there is currently only one question tagged russia on Law.SE. If this tag should be zapped, the question would be in violation of Law.SE's de facto policy that all questions specific to a particular jurisdiction should carry a corresponding tag. Similarly, Arqade has only one question tagged pitfall, and likewise asks for all questions to have a tag identifying the game. Commented Jul 23, 2015 at 3:24
  • @JohnSaunders (And it's not as if those tags are misnamed or misspelled; as far as I can tell, only one person on Law.SE has asked about Russian law, and only one person on Arqade has asked about the game Pitfall.) Commented Jul 23, 2015 at 3:26
  • Ok that should be in your answer. Thanks. Commented Jul 23, 2015 at 3:41
  • @JohnSaunders: I have rewritten my answer; hopefully it is more clear now. Thanks for your comments. Commented Jul 23, 2015 at 3:49

I think any tag that is only used a few times over a few months should be hidden and not shown on any questions or in the list of tags.

If it gets type into the tag box, it should then be unhidden for a month.

That way if it takes a few month before a tag is used more then 1 or 2 times, we don't loose the tagging info from the first questions it was used on.

  • Why? I don't understand the win.
    – beska
    Commented May 18, 2010 at 16:53

Here's a datadump query that will give single-use tags older than 3 months:

With SingleTags As
  SELECT Tag FROM PostsTags GROUP BY Tag HAVING Count(*) = 1
SELECT st.tag, p.ID As PostID, p.Title, p.CreationDate 
FROM SingleTags st
INNER JOIN PostsTags pt ON pt.tag = st.tag 
INNER JOIN Posts p ON p.id = pt.postid 
WHERE p.CreationDate < DateAdd(m, -3, getdate())
ORDER BY p.CreationDate

And I know it's not stable right now, but here's the StackQL results:
And here's a similar query on the StackExchange Data Explorer:

Quite a few of these tags are already cleaned up.


How many of Stack Overflow's current tags have at least a 6 month gap between their first and second use? Probably not very many (if any - would make an interesting odata query). Certainly not enough to justify keeping the single-use tags around.


What is the point of keeping tags that are used by one or few users? When tags is quite popular, I can hope that someone will view questions with this tag and, coming across the problem he knows the solution, he will answer it. When tag has 10 questions, who will visit its page regularly? Except for search engines?

Such tags, in my opinion, poisons the tag system, because many users use such tags, when other, more popular, would be appropiate and would increase their chances to get answered. When there's too much options, making good choise become more challenging.

The exception are, of course, new technologies, which began to be popular and tags for them should be created, so that other users will see it and use when needed.

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