It seems to be widely believed that...

"comments are ephemeral" - Everyone on SE

and ephemeral means...

e·phem·er·al [ih-fem-er-uhl]


lasting a very short time; short-lived; transitory

So, the facts...

  • Comments can only be deleted by the owner, and the select few with Moderator privileges.
  • Unlike posts, comments can't be changed/edited (except for the first 5 minutes, and only by the owner)
  • There are only 2 reasons to even flag a comment
    • Is rude/abusive (applies to everything)
    • Is not/is no longer necessary (If comments are really ephemeral, shouldn't these clean themselves up by the definition of ephemeral?)
  • Users can't lose reputation because of their comments. (They can be banned, but for the same reasons as all other posts, but harder for Mods to see a behavioral pattern)

The best explanation of this mindset I could find is here

From that answer

The user who posted them or a moderator can delete them at any time, that's just stating a fact, I'm not discussing intent,

So just like posts, only much more restricted. Except for an edge case with questions related to holding you accountable for the people's time you've wasted

Regular users have no way of seeing deleted comments, they are only available to moderators, in contrast with deleted questions and answers which can still be accessed by regular users with more than 10,000 reputation,

cus, ya know, so many people have 10k+ rep

Moderators don't have access to a central list of deleted comments, if they don't know that a comment was deleted they might never find out.

So, because Mods have an incomplete toolset

The reality seems to be that comments are nearly permanent. And carry far less accountability than normal Q&A posts.

It would be interesting to see the average lifespan of a deleted comment vs a deleted post...

We all know SE won't put a Time To Live of comments, because sometimes they are important, and need to live for the life of the Q or A. (Which, is probably a sign that a suggested edit is required, or is in some way an addendum or sub-answer)

So, to reiterate the base question; If comments are ephemeral, why don't they expire? If they are pseudo-permanent, why does everyone say they are ephemeral? In what way are they "short lived" compared to Q&A?

  • 6
    Couple of corrections to your facts: 1. "Comments can only be deleted by the owner, and the select few with Moderator privileges." Actually, comments can be deleted automatically if enough people flag them, and comments with certain keywords can be deleted instantly after a single flag. 2. Moderators can edit comments even after the 5-minute threshold for the OP to edit. 3. Those are not the only two reasons comments can be flagged; you can type in a custom reason instead. Jul 2, 2018 at 19:11
  • 3
    Perhaps "temporary" would be a better word to use.
    – ale
    Jul 2, 2018 at 19:39

1 Answer 1


Some corrections:

  • Comments can be deleted via flags without moderator intervention in some cases.

  • "No longer needed" covers a wide range of cases, from "obsolete because the post was edited" to "this 37-message discussion on a tangential topic doesn't belong here". ("Was never needed" is considered by SE to be a case of "no longer needed".)

  • I don't know about "everyone on SE", but many people phrase that as "comments are meant to be ephemeral". The distinction between design intent and implemented reality is important.

Now, to your definition: the word you want to focus on there is "transitory", as in "might be here tomorrow, might not, but you shouldn't expect it to be permanent". There are no automatic time-outs; a few comments have lasting value (for example, links to related questions/answers), and many would be deleted if anybody noticed but nobody did and the thread didn't get out of hand so they stick around. That's by design; a machine can't determine which comments are valuable so we rely on people, and people neither provide complete coverage nor are 100% consistent.

Fortunately it's just comments, not something important. If moderators started deleting posts that fall outside a narrow range there'd be justifiable outcries on meta; with comments there are sometimes outcries, but rarely are they justifiable.

If you want something to be durable, put it in a post. If your comment sticks around longer than you expected from the definition of "ephemeral", consider it either an oversight or a gift.

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