Comments are impermanent. They've always been meant to be. The problem is, unless a moderator goes through a question and physically deletes the comments, they're pretty permanent.

Why is this a problem?

Comments distract from their parent post. Often, comments contain information that is better suited to be in the post itself, or better suited to take place somewhere where extended discussion is welcome.

Comments are almost always a point in time blurb. They don't have the edit history of a post, and they don't flow logically as a post might. They are purposefully unstructured.

In short, comments are weeds that grow up around the useful questions and answers, and because it is impossible to prune them sanely through any human means, they proliferate, and cause a user to have to read not only the answer, but all of its comments, and attempt to parse out the relevant points from the non-relevant ones.

Yet, by default they are permanent, insofar as they remain around unless deleted by a moderator (or flagged often enough that they're deleted by the Community user)

This should change.

Comments are meant to ask for clarification, or to address points that are meta to the post itself: whether it should be closed, re-opened, or deleted.

Once that clarification is received, it's always better to put it somewhere where it will be seen by a googler: into the relevant post (either the question or the answer the comment seeks clarification on).

Feature Request

Comments should be auto-deleted after a period of time (a year is a good starting point for discussion), and this should be communicated to those that leave comments in a non-obtrusive way. This non-obtrusive message should be shown to the user the first time they leave a comment.

Part and parcel to this is an appropriate merging of the third place with a post. If people want to chat about a question, the third place should automatically set up a link to the question so that people can chat there. I recommend a 'chat' link right next to the 'edit' link for users that have the ability to chat.

If you disagree with this feature request, then please share posts where a comment was left years ago that is relevant and useful now, but shouldn't be 1) its own answer, 2) its own question, 3) an edit to an existing answer or 4) an edit to an existing question.

This related question talks about a user being able to set an expiration date on comments. Another older feature request asks for very much the same thing. I'm not asking for such complexity. All I'm asking for is that all comments are deleted after 1 year.

Please note: This feature request is primarily for Stack Overflow. We see thousands of new posts a day, with the potential for tens of thousands of comments a day. There is no level of flagging that could even come close to dealing with the number of irrelevant comments lying around. Even if there were enough flagging, there aren't nearly enough moderators to deal with the resulting flags.

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    Hopefully, this comment will disappear in a year.
    – yannis
    Commented May 13, 2013 at 16:55
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    Like it or not, there are a lot of valuable comments out there, and it doesn't always make sense to edit them into a post as it might be something tangentially related to the post. Perhaps it would make sense with an exception for comments with more than X votes or something like that?
    – hammar
    Commented May 13, 2013 at 17:13
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    @nhahtdh then flag those comments as chatty. It's the work of moments. Commented May 13, 2013 at 17:18
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    Another problem is comments on wrong answers. It doesn't make sense to edit into the answer "this answer is wrong", and there are cases where it is not possible to fix the answer.
    – nhahtdh
    Commented May 13, 2013 at 17:18
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    What about "This accepted and highly upvoted answer is massively dangerous for reason X, please see answer Y instead" with 50 upvotes. I don't believe that should be removed. Commented May 13, 2013 at 17:19
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    Agree with @nhahtdh, especially if those comments go into some depth to state why the answer is problematic. Those don't necessarily make appropriate answers. Nor do downvotes explain the reasoning. Deleting those would leave a downvoted question with no apparent reasoning.
    – Bart
    Commented May 13, 2013 at 17:19
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    If you disagree with my premise, then find posts where comments should stick around that are years old using one of the criteria I listed above. It's ok not to like a feature request, but without data, it's just an emotional attachment. Commented May 13, 2013 at 17:29
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    It's hard to pull up a recent example, because I haven't found any particularly recently, and don't remember the last time this happened. They can definitely be useful, though, for identifying wrong answers - an OP refuses to delete their upvoted post, but a comment says it's wrong. That's saved me a couple times (though I don't remember exactly where)
    – user206222
    Commented May 13, 2013 at 17:40
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    @GeorgeStocker The jump from "they should perhaps have been made into answers" to "so let's get rid of them altogether" is a rather extreme one. Even if something is better permanently kept around as an answer, blindly deleting the content surely is not great either.
    – Bart
    Commented May 13, 2013 at 18:07
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    -1 This encourages two bad behaviors: Not an Answer and Invalid Edits. That is, people will turn comments that give partial solutions (like "I found that your problem didn't occur before version 11.3") into answers just so they won't get deleted, and people will edit "This won't work because of X" into answers. Commented May 13, 2013 at 18:13
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    I agree with the Problem (too many useless comments) and I wholeheartedly support changes that would make it easier for the community to delete unnecessary comments, reducing the burden on mods. But I strongly oppose the automatic expiration of comments, regardless of the content.
    – joran
    Commented May 13, 2013 at 18:15
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    @jalf: I think your comment is going a bit too far. The motivation here is to put the important information where it should be, and remove the noise. Reading a post, then having to read through the comments is not very efficient.
    – nhahtdh
    Commented May 13, 2013 at 18:24
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    @Bart Show me. Show me one single question that "drowned" in the noise of comments. Individual comments can drown, sure, but except in a very few pathological cases, the comments are not what causes good answers to drown.
    – jalf
    Commented May 13, 2013 at 18:25
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    @jalf Then come up with a great way to preserve the valuable comments while effectively reducing and removing the noise. That has been my whole argument from the start. Comment upvotes don't achieve that in my opinion.
    – Bart
    Commented May 13, 2013 at 18:36
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    @Gordon: and comments which are made in low-traffic subjects where they don't get as many upvotes? Automatic deletion of comments is a horrible idea, period. Automatic flagging for review and possibly manual deletion could make sense, but we've seen before that a moderator passing through made the wrong call and deleted a string of valuable comments.
    – jalf
    Commented May 13, 2013 at 18:54

6 Answers 6


If you come across an obsolete comment, flag it as such. I'll often flag a whole collection that look like this:

  • Could you include some code please? - somebody
  • We really can't help you without any code - else
  • oh sorry guys i will add it when I get home - OP
  • thanks that's much better - somebody

All four of those can and should go. Not in a year, either - the minute you see them. Waiting a year to delete them would be wrong.

In contrast, comments like "actually I don't think that's possible" or "here's a related question that isn't a duplicate but might help you" (on a question) or "this answer is obsolete and does not work with the latest version" (on an answer) should NEVER be deleted and should not become answers either.

I don't see a use case: you would need a comment that no-one with flagging privileges has seen for months and months, yet it is somehow confusing people or taking up space. Just not a likely scenario for me. Far better to put your effort into encouraging people to remove their own obsolete comments and flag other people's.

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    I'm a moderator on Stack Overflow. I can say with authority that if the only mechanism to delete comments were moderator flags, we'd be in a lot of trouble. As it stands, we are. We get thousands of new posts a day, and I bet most of those have at least 1 comment (if not two). That means we could have tens of thousands of new comments every day. That's why I call them weeds. Their growth seems geometric, where the pruning is not. 9 moderators do not scale. Users won't delete comments unless they get some sort of reward for doing so. Commented May 13, 2013 at 17:19
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    Then let's make a review queue for the addicts who keep all the other review queues (except close) at zero and let them confirm that comments are obsolete. There's doubtless a badge in it and even if there isn't people will do it. I'm over 10k; can I do it now? Commented May 13, 2013 at 17:21
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    @GeorgeStocker How many obsolete flags does it take for a post to be deleted? If they always need a mod to be deleted, why not introduce auto-deletion after X flags?
    – Servy
    Commented May 13, 2013 at 17:21
  • I see hundreds of comments every day that are useless. The number of gems that I've seen that should stay around for the rest of time is so small that they're almost irrelevant. Commented May 13, 2013 at 17:22
  • @Servy That exists already. If enough people flag a comment, it goes bye-bye (if it's not upvoted). The problem is, people don't flag comments enough, and even if they did, there aren't nearly enough moderators to sanely check the comments. The only viable solution is to systematically enforce the idea that comments are not permanent. Commented May 13, 2013 at 17:23
  • @KateGregory The biggest worry I have there is that currently with all of the review queues if the wrong action is taken I'm capable, as a non-mod, of reversing the problem. I can rollback an edit, re-close a reopened question, reopen a closed question, undelete a deleted post, etc. But if a comment is wrongly deleted only a mod could undelete it...
    – Servy
    Commented May 13, 2013 at 17:23
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    @Servy I'm not sure if mods can undelete comments at all...
    – Mysticial
    Commented May 13, 2013 at 17:24
  • @Mysticial We cannot. That's on purpose. As Jeff Atwood has said many times, if you want something to stick around, put it in a question or an answer. Commented May 13, 2013 at 17:25
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    @GeorgeStocker on Mi Yodeya, where I am a moderator, staying on top of comments really isn't a problem. We need to be careful not to make SE-wide policy based on SO alone. Maybe things are broken on SO (I wouldn't know) and if so that needs to be fixed, but one size definitely does not fit all here. Commented May 13, 2013 at 17:25
  • Couldn't agree more @MonicaCellio. I'm a mod on Drupal Answers and I wouldn't like to see this implemented there
    – Clive
    Commented May 13, 2013 at 17:25
  • @MonicaCellio Great point. I placed that clarification in my question. Guess what? Now these 4 comments are irrelevant, but will likely stick around for years even though they serve no purpose. Even better would be if you made your point into an answer, Monica. Commented May 13, 2013 at 17:30
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    @GeorgeStocker how exactly is it a problem if most questions have "a comment or two"? That's not what I would call excessive noise. I think the problem is that you have decided that comments are, by default, harmful and noisy, and that you have decided to elevate them to the status of "a problem". Who cares if every question has a comment or two? If every question had 20 comments, I'd agree something was wrong (and then the focus should be on reducing the need for comments, not on deleting the comments that people post anyway. But you haven't made a case as to why comments are a problem
    – jalf
    Commented May 13, 2013 at 18:31
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    @GeorgeStocker: Comments that express disagreement, but can not be edited into a post (a common situation with more subjective topics) are potentially quite valuable. Meta sites are one place your feature request should never be considered. If the disagreement is resolved, a case may be made that such comments are obsolete, but there can still be value for future users in knowing who argued what and how. Commented May 13, 2013 at 19:26

I'd like to suggest an alternate solution.

Co-opt the review queue feature to have an "old comments evaluation" option. This would work as follows:

  • Any post that is older than 1 year and has more than 2 comments is entered into the queue.
  • The reviewer sees the whole comment stream and then has several action options

    • Flag individual comments (streamline flag dialogue here).
    • Vote to purge entire comment stream
    • Vote to keep comment stream
  • At 5 votes to purge all comments are purged from the post

  • At 3 flags on any individual comment is removed
  • At 3 votes to not-purge the post is removed from the queue and cannot reenter it until the post is edited.

This allows for the users to decide when to keep comments and when to purge them and it allows for this via a mechanism that's already in place instead of relying completely on moderators to delete comments.

Note: this should be a high rep queue, maybe even 20-30k+ feature.

  • That's a really good alternative request. I like it. +1 (intentional irony: future-useless comment indicating +1) Commented May 13, 2013 at 17:43
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    This idea is fine as long as there is a way to undo any damage done by robo reviewers. (i.e. ability to undelete comments.)
    – Mysticial
    Commented May 13, 2013 at 17:43
  • @Mysticial while that isn't in place at this time, it is in the works.
    – wax eagle
    Commented May 13, 2013 at 17:45
  • @Mysticial Late to the party here... maybe some sort of "purge-gatory" for deleted comments, from which they could be resuscitated by mods if their authors are upset by their removal.
    – hBy2Py
    Commented Dec 14, 2016 at 15:20

The idea that comments are always used to add information to the original post is nice, but it is also not terribly realistic. We should design such features against the real situation, not against the situation we would like to have. And in practise, there is often enough useful information in comments that isn't incorporated into the answer.

Comments have very low signal to noise compared to real answers, but that doesn't mean they are completely useless. They are still easy to ignore if you want to.

The biggest case where I think this would hurt SE are comments that point out errors or weaknesses of an answer. Not all answerers are receptive to criticism and enough won't correct their mistakes. A hostile edit of the answer by the commenter is also something that is usually not done on SE sites. Theoretically the commenter could expand this into a full answer, but that puts a much higher burden on anyone that just wants to correct a wrong answer.

There might be some value in a system that automatically hides comments after a while, but I think that actually deleting them would cause more collateral damage than it is worth. Another idea would be to show comment flags to 10k users, which would make it easier to remove truly useless comments.

  • Furthermore show not in a queue but as part of the UI when viewing a page/comment. Probably should be opt-out'able for 10k users; many like cleaning up the site, some may not appreciate the extra work that comes with their doing extra work. obso comments can probably be handled by 3k+. Plus doing this raises awareness of the feature - I'm 9k SO / 3k here and just learned of this
    – djechlin
    Commented May 13, 2013 at 17:46

If you disagree with my premise, then find posts where comments should stick around that are years old using one of the criteria I listed above. It's ok not to like a feature request, but without data, it's just an emotional attachment.

This comment, is IMHO, instructive, and relevant to the issue at hand but is not part of the direct answer to the users question.

It is also general, i.e. they are not likely to change the standard that anchor tags and list item tags are inline elements, any time soon. Which means that the comment isn't likely to be outdated any time soon.

I have come across tons of comments like this, that actually led me doing something different then what I had originally intended. And they were on good questions that lots of people used. They are related they are useful, they make the internet a better place but they are not exact fits to the OP's issue, however they have helped lots of other people solve issues similar to the OP's.

Isn't the goal of SE to make the internet a better place? Why delete this type of content even if it's not directly related when it has actual value?

If you would like to go through the thousands of comments like this and make questions for them and then make the comment into an answer for that question, then go for it. I would fully support you on that. But until someone wants to do that then the comments should be left alone.

  • 1
    Your comment should be edited into your answer. It's good information, lost in a sea of comments on that post. If you hadn't linked me directly to it, I don't think I would have noticed it with the comments that are around it. Commented May 13, 2013 at 18:04
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    @GeorgeStocker if I'm actually going to implement something I learned from an answer, I read the comments.
    – djechlin
    Commented May 13, 2013 at 19:28

One alternative: Make permanence opt-in via a check mark instead of default. I strongly suspect this might do the trick, as users will stop and think "Will this be useful for a long time or just until the OP incorporates it?" and this may clean up itself.

Or let post owner be able to mark a comment as "completed" and get rid of it. Many comments are to-do's for the OP (e.g. "can you post your output?") and can go away when incorporated. Would work on answers, not on lowish-quality questions.

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    I'm not a fan of checkboxes for many reasons, not the least of which is that they introduce complexity. Commented May 13, 2013 at 17:16
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    Or let post owner be able to mark a comment as "completed." Once a comment is "complete" it can and should just be deleted. If you as a poster to incorporate X into their post and you notice that they have; just delete the comment. If it's not yours, flag the comment as "obsolete" so a mod can delete it.
    – Servy
    Commented May 13, 2013 at 17:17
  • @Servy yes, that's what I meant - "completed" means "therefore get rid of it." Like closing an issue.
    – djechlin
    Commented May 13, 2013 at 17:18
  • @djechlin But we don't need a new feature for that. You can already do exactly what I described.
    – Servy
    Commented May 13, 2013 at 17:20
  • @Servy, one, people don't (even I didn't know this was good practice), two, if they did, moderators could not keep up, per George's comment on Kate's answer.
    – djechlin
    Commented May 13, 2013 at 17:22
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    @djechlin People should, primarily, be deleting their own comments. That does not require moderator interaction. Second, for the obsolete flags, they result in deletion after X flags already, again, no need for moderator interaction. So we just need people to be encouraged to flag obsolete posts and that's it; the rest is all already in place.
    – Servy
    Commented May 13, 2013 at 17:25
  • @Servy oic. I didn't realize we had an explicit obso cat that does that. thx
    – djechlin
    Commented May 13, 2013 at 17:45
  • @Servy I agree that people should be deleting their own comments. However I bet I have many, many comments where I suggested an improvement to a post, the OP made the improvement, but didn't let me know. Like down-votes, I am left on my own to go manually review my comments to see if they were acted on. I'd like to see an easy way for the post owner to let me know they've addressed my comment, rather than flag it as obsolete or post an @ reply to every commenter. It should be a simple click.
    – Aaron Bertrand Staff
    Commented May 14, 2013 at 1:35
  • @Servy also while users can flag a comment as obsolete, there isn't much value for anyone to do that, including the post owner. And even if they do do that (I suspect many don't know they can or should), nobody else is notified. So other users must also want value to flag, or we push the burden onto moderators. This seems like a complex solution to a simple problem.
    – Aaron Bertrand Staff
    Commented May 14, 2013 at 1:39
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    I don't think the post owner can solely decide that a comment has been made obsolete (I think the commenter should have to agree that you've correctly addressed it), but I do like the idea. If they can't agree then the comment stays unless someon else flags it and a moderator agrees.
    – Aaron Bertrand Staff
    Commented May 14, 2013 at 1:52

I don't realistically see this to be a massive, overwhelming problem, at least not to the point where we need to go to such extremes -- extremes that don't take into account the fact that not every site is the same, not every post is the same, and not every post has received the same care from the skilled hand of an editor.

Initially, Stack Exchange intended comments to be transient, and in many ways, they are. But in other ways, they've become much more than what the founders of Stack Exchange intended. Sometimes users use your product in ways you didn't intend, and sometimes it's best to meet your users in the middle if the alternative of forcing that vision on them would prove to be harmful.

I do agree there are examples of comments on posts that I'm sure could be removed. However, in a large majority of these cases, comments are not actively harmful nor are they crippling the focus on the Q&A. While it's possible the Q&A might benefit ever so slightly from their removal, such an authoritarian, draconian, blanket removal of all comments in the system may create challenges that outweigh the perceived benefits.

We need to keep in mind that we're dealing with human beings, not robots, and while Stack Exchange is not a social network, some mild discussion is not harmful nor do we actively discourage mild discussion.

Part of the definition of a not-constructive post is that the material may lead to to extended discussion not any discussion. While extended discussion clouds and muddies posts and makes them extremely difficult to read, a few comments here and there mostly do no harm and may add additional value that could be edited into the post but for whatever reason haven't.

As a moderator on The Workplace and Project Management Stack Exchange, I believe that systematically removing every single comment for the sake of removing them would create issues in the community. These communities have made their own rules, taking into consideration the vision of Stack Exchange while still tailoring the model to fit that community's specific needs. Blanket deletion would make many users in these communities feel like we're forcibly silencing them, and I would feel the same way as a user on Stack Overflow if comments started disappearing without any human intervention.

Now, if discussions extend beyond just a few comments, and the comments are flagged, or if the system auto-flags a post which has more than 20 comments, then I'll take action and do a comment cleanup. I've also flagged long conversations on Stack Overflow for being too verbose, cluttering up the page, so I'm not against the idea of tidying up, just the idea that one-size-fits-all approaches will solve the world's problems.

  • This is only for Stack Overflow. Commented May 15, 2013 at 11:59
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    Regarding the "I'll take action and do a comment cleanup", that's all well and good, until you have hundreds of thousands of questions that need that to happen. It's a difference of scale. If it were a dozen posts, that's one thing -- but we're talking thousands of posts. Commented May 15, 2013 at 12:00
  • There are over 50,000 posts with greater than 10 comments on Stack Overflow (incidentally, 50,000 is the max number of rows a SEDE query can return). SuperUser, which is the next largest site, only has 2215. That's the difference we're talking about. Commented May 15, 2013 at 12:12
  • What about organizing a comment cleanup instead, sort of like we do on tag cleanups? I'm sure there are plenty of people who would love to make an impact here and help with this.
    – jmort253
    Commented May 15, 2013 at 14:22
  • That's great for a one time effort, but as I've seen with the 'Fixed'/'solved' issue, it keeps coming back. With comments, that's even more difficult, since we get many more of those a day. Commented May 15, 2013 at 14:33
  • I'm not worried about downvotes. :) They're like mosquito bites. Don't scratch them, and eventually you forget about them. I definitely don't have the answer, and it's good you proposed this as a solution because it's at least getting us all thinking about it. Another suggestion is doing something that may help change the culture of how we as a community think about comments. Maybe you could discuss with the community team a way to launch a campaign to clean them up and change how we think of comments. Summer of Love, for instance, wasn't perfect, but it did have lasting effects!
    – jmort253
    Commented May 16, 2013 at 1:07
  • To clarify, an official SE blog post motivating and encouraging us all to clean up our mess may be a healthy way to stymie this problem, but without forcing the titanic to change course. One thing about SE is that people love to control their own destiny but panic when someone else tries to control it for them. Hope this helps!
    – jmort253
    Commented May 16, 2013 at 1:09

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