I used my popular question Do Projects Ever End Early? as the basis of a book I wrote.
(Available for free, for a limited time, here.)

What is the appropriate protocol to inform the 14 users whose answers I included, as well as all those who commented, that they are being quoted?

I mention each user by name and add their profile URL in the footnote. A screenshot:

Enter image description here

I wrote a comment to this effect under the question. Should I add a comment under each answer @pinging the user? It seems a bit over the top. AFAIK, there isn't any way to PM users on SE.

(For the record, I researched this before I started writing, and the Stack Exchange license allows quoting in this way.)

  • 15
    You're not required to inform anyone that you're using their answers. You just have to attribute the answers correctly.
    – cigien
    Jan 16 at 12:58

3 Answers 3


Per the various licenses that users may have contributed their work under (CC BY-SA 2.5, CC BY-SA 3.0, or CC BY-SA 4.0, at time of writing), you do not need to notify the original author if you re-use their work. However, it is sometimes polite to do so!

AFAIK there is no way to PM users on SE.

There's the next best thing: invitation to a chat room. Set a descriptive room title, invite all the users who have chat profiles, and the message will appear in their inboxes. You can place further information in the room.

Stack Overflow and Meta Stack Exchange have their own chat servers (SO, mSE), where the user ID namespace is the same as the main site, and chat profiles are automatically created when the profile page is visited for the first time. Any user with at least 20 rep on one of these sites can be invited to chat. Network chat has a different user ID namespace, and afaik only moderators can create chat profiles for other people.

  • 5
    I don't think a chat room is really the best. It'd require all users to at least be in chat already (for the same server). Only then can they be invited to a room and that would notify them. Otherwise just @-mentioning won't notify them - this would ping a user given they have recent activity in the room. User mentioned in room A won't be notified in room B if they had no activity in A. Only mods can "super-ping" from any room.
    – VLAZ
    Jan 16 at 13:14
  • 1
    @VLAZ It's not a good solution, but I think it's the best we've got. Most active users have a chat profile, and afaik that's the only requirement for invitations to notify. That'd leave fewer comments needing to be posted (since each comment can only notify one user).
    – wizzwizz4
    Jan 16 at 13:22
  • 3
    A remark for the readers: Not all users might be invited to a chatroom. They should have used the chat platform, etc.
    – Rubén
    Jan 16 at 13:40
  • @wizzwizz4 ah, this always gets me. Yes, they are different, I'll re-post my comment, sorry. Jan 17 at 19:18
  • 2
    @Rubén when you visit the chat profile of a user in Stack Overflow or Meta Stack Exchange by manually appending chat. to the profile URL (both have their own chat domain and server). it is automatically created even if that user never visited it. You're correct about the se.com chat though, unless the user visited their own profile, it's impossible to invite them. Jan 17 at 19:21
  • @ShadowWizardLoveZelda I was referring to inviting someone to chat in a broad sense, not in the operational sense (clicking a link). It doesn't make sense to click a link inviting someone to chat if the invitee cannot chat.
    – Rubén
    Jan 17 at 19:27
  • @Rubén If you want them to be able to chat, sure. If you're using it as a hack to add a notification to their Global Inbox, that doesn't matter (unless you're saying that <20-rep users don't receive notifications for chat invites).
    – wizzwizz4
    Jan 17 at 19:54
  • 2
    @wizzwizz4 you can't invite users if they have less than 20 rep, there's no invite button. Only a moderator can super ping such users, and by this sending them instant notification, but ordinary users can't do that. Jan 18 at 6:58

I think a comment is a good way to do this.

For the author of the answer, it will notify them. Even if the comment ends up deleted, they will have received the information that you found their answer useful in this way.

For others, the comment is generally useful (there are tons of comments that say things like "this is the best answer I have ever read on this site" or "I signed up for this site just so I could upvote this") as a measure of the quality of the answer. It may also be helpful to people who have read the whole answer, if you include a link to the book, so that people can read more on the topic. That's especially true if you expand on the answer or use it as a starting point for your own work in the book.

Sure, some of the answer authors won't be active any more -- but in that case you'd be unlikely to reach them any other way anyway. And sure, some of the comments might get deleted on a site that doesn't like "this is a great answer" comments. But I think that's an ok outcome if the authors saw the comment before it was deleted - comments are ephemeral.

The comment has the least impact on everybody else -- a chat room with 14 people who don't know each other feels odd to me, a meta post on each relevant site with links to the answers brings in people who otherwise wouldn't read those answers, and so on -- while at the same time being most likely to reach the original answer authors you want to reach.


Private Messages

Look at the user card or profile of the user that you want to send a private message to. Some might add a way to PM them; some might mention that they hang around in a chat room and could be found there.

Chat Platform

The chat platform doesn't allow regular users to PM other users. They could invite a user to a new chatroom, but the chatroom messages are public. Only "diamond moderators" can make a chatroom private, and this is intended to be done for moderation purposes.

Regarding Comments

I understand that the "Comments" features are intended to improve the post by asking for clarification and providing guidance to the OP and the post's editors.

As the referred question was posted in Project Management, check out the help article from the Help Center of that site, their Meta:

Please bear in mind that each active community, the group of active users able to post comments and moderate on a specific site, might use this feature in a particular way and have different tolerance levels to deviations from the intended purpose. Also, each community might have its own etiquette. Because of this, you should ask this question on the per-site/child Meta of the site where the question was posted. The use of comments, and the etiquette, among other things, might have evolved as old users abandon the site and new users have a different way to understand and do things.



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