When does the system automatically modify content (such as votes, question, answer, or comment text)?

What automatic changes does the system make to

  • questions?
  • answers?
  • comments?

This FAQ should help new users understand potentially surprising behavior to avoid erroneous bug reports and recurring questions such as new users are asking why their posts don't come out the way they typed them

  • 1
    Most of what you are looking for can be found here – user102937 Jul 5 '11 at 22:38
  • @Robert: I'm not asking or an engine change or anything like that. Nor am I attempting to be belligerent. But I think we do need some place to point people when they're asking what's going on. Honestly, I don't intend to sound annoying or petulant. Really, while that recent question is the reason I was thinking about this enough to ask a question like this, I'm not trying to cast a bad light over system modifications as a whole at all. I just think it would be nice for a canonical reference to exist that would explain what's going on to people. Do you have other suggestions? – Billy ONeal Jul 5 '11 at 22:40
  • @Robert Well yes, but that post is a bit lengthy – Michael Mrozek Jul 5 '11 at 22:40
  • @Robert: Good idea. I'll construct answers from that post. Thanks! – Billy ONeal Jul 5 '11 at 22:41
  • I deleted my comment after I figured out what you were doing, converted to wiki, and upvoted. </sheepish> – user102937 Jul 5 '11 at 22:42
  • @Robert: Lol -- sorry, was just worried that this would be taken as malicious. That's not my intent at all. (I'm trying to be constructive here. Plus, I don't want a big S! ) – Billy ONeal Jul 5 '11 at 22:44
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    @Billy: I've deleted mine and rolled the relevant part into your answer (the link to the changelog). – user7116 Jul 5 '11 at 23:06
  • @sixlettervariables: Thanks! :) – Billy ONeal Jul 5 '11 at 23:07
  • Would it be worthwhile to list common "manual" modifications such as removal of "thanks" and removal of tags from titles? These changes might also be surprising to some users. – Rick Sladkey Jul 5 '11 at 23:25
  • @Rick: I don't think that's necessary. There are links that say "This was edited!" which show such users what's going on. – Billy ONeal Jul 5 '11 at 23:26
  • I can tell you from experience that that indication is of no comfort to some users. But I understand your point. – Rick Sladkey Jul 5 '11 at 23:30


  • If a question is closed as a duplicate, its title will be rendered as Original Title [duplicate].
  • If a question is closed (not as a duplicate) within the last five days, its title will be rendered as Original Title [on hold]. If it was closed (not as a duplicate, again) more than 5 days earlier, its title will be rendered as Original Title [closed].
  • If a question is migrated to another site, its title will be rendered as Original Title [migrated]
  • If a question was migrated from another site and subsequently closed for any reason, its title will be rendered as Original Title [migrated] in search results only.

Note that the above rules only apply to the website (including the mobile site), not the mobile apps. On the mobile apps, no title modifications are performed when viewing the question, only in question lists. There, the first three above rules apply, in addition to the following ones:

  • If the question is protected, its title will be rendered as Original Title [protected].
  • If the question is locked, its title will be rendered as Original Title [locked].

Additionally, in both the app and the website:

  • Tags using [tag] notation are automatically stripped from titles.
  • Exclamation marks at the end of titles are converted into question marks.
  • "Straight quotes" in question titles are converted into “smart quotes”.
  • The sequence "--" is converted into an em dash ("—") in question titles. To force it to display as "--", put an invisible character in between the two dashes, like in the following sequence: -​-


All Posts

  • Greetings are removed automatically from both questions and answers before they are posted.
  • Internal links to questions are converted into links as the title of the question. For example https://meta.stackexchange.com/questions/97524/list-of-reasons-for-automatic-system-content-modification gets converted into List of Reasons for Automatic System Content Modification.


  • In comments containing @replies to the post owner, the @reply will be removed from the comment text if it is at the beginning of the comment and the author has not commented, as it is not needed (the post owner is always notified of comments on their post).
  • When a question is closed as a duplicate, any comments on the question beginning with "possible duplicate of" and containing a single URL that points to the closed-as-duplicate-of question are automatically removed at the time of close.2

Information above is taken from: Recent feature changes to Stack Exchange.
1 This applies even if the user posting the answer doesn't have enough reputation to post comments.
2 New duplicate comment rule taken from Automatic removal of comments when a question gets closed as “exact duplicate”

  • 1
    actually, the [close] / [migrated] is not appended to the title of the post, it's shown based on the type of vote – Sathyajith Bhat Jul 6 '11 at 6:57
  • @Sathya: Is there any observable difference for the user whether or not it's stored in the database with the title changed or not? – Billy ONeal Jul 6 '11 at 16:31
  • 2
    @BillyONeal Well, it isn't present in the title field if they go to edit the question after it's been closed. Not sure if that makes a difference or not. – Tim Stone Jul 6 '11 at 16:43
  • @Tim: Fair enough. @Grace Note: Thanks for fixing it. :) – Billy ONeal Jul 6 '11 at 17:02
  • You're welcome. We actually don't have that update on the duplicate stuff shown on this site yet, to my recollection, so here's as good a place as any to get the debut. – Grace Note Jul 6 '11 at 17:13

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