I have recently noticed that there are different strategies of people to work with comments:

• Some add a short note that the question (or answer) will be changed as a reaction to the comment.
• Some only change the question (or answer) without a comment.

See for example the answer of myself to the question remove svn username , password eclipse is not working in windows 7 . I have just added a small note in the comment, the answer does not state what is old and new content. And the questioner has appended a section EDIT to make sure that the people see the difference.

I think I have an understanding what the proper way should be, but I would like to get your answers first. (And yes, there should be following another question how to teach people to behave like that, but that's another story.)

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I think what you should generally strive for is a question-answer pair that in itself is consistent. That means: Imagine you're a visitor who doesn't know about the process behind writing this question and answer. What would you rather like to see?

• A question with an answer that fits the state of the question. Both seem to be written in one piece.
• A question with multiple EDIT: paragraphs added, and an answer that does the same.
• A question with lacking details, only found in the comments (same goes for the answer).

I think we can agree that the first option is the most desirable.

If you can, always update your original post. In the case of a question that means to always include the most recent information, for example if there's a comment asking you for clarification. This does not necessarily have to be a ton of EDIT:s added. In many cases it would make more sense to reformulate the question – if and only if it helps others (new visitors) to understand it better.

As an example: Why should you mention "Edit: I uninstalled the old version XYZ before" at the bottom of a post, rather then mentioning it where it fits chronologically, e.g. right at the beginning of a post: "I uninstalled the old version, and then tried to install version XYZ".

When everything's up-to-date, commenters asking for clarification can be notified, and if they've seen the changes, their comments might also be flagged as "obsolete" – I've been doing this many times in order to remove … well, obsolete information.

For an answer, the same thing applies. Make your answer consistent in itself and with regards to the question. Always update the post, and reformulate if necessary. Don't clutter it with EDIT:s.

The whole point is: Make it easier for those not involved in the evolution of the Q&A to understand what's going on. It can be very hard to comprehend the timeline behind subsequent edits, clarification comments, etc. Remove the clutter, and we'll all be happy.

Concrete examples:

### Ruby on Rails: what is the default rails version?

This really looks awkward, does it? Why can't the important information be in the answer itself? Update the answer to include everything we know, and then eventually delete the comments.

### remove svn username , password eclipse is not working in windows 7

This looks strange too. The question is hard to understand, and it could be restructured. My point is: I don't care about the fact that the OP edited the question (I can see it in the revisions, if I want). All I want is all the information the OP can give me. It doesn't need an EDIT appended. And it certainly shouldn't be buried in a comment somewhere.

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By the way, I've edited the question in the second example to make it easier to read. –  slhck Dec 11 '11 at 11:12
Very nice answer, thank's a lot. One question: How do you flag a comment as obsolete? I did not find any hint anywhere how to do that. And my reputation is not sufficient yet. –  mliebelt Dec 11 '11 at 11:13
Click the flag next to the comment, then choose the obsolete option. This is similar to my request about obsolete comments on migrated questions. –  slhck Dec 11 '11 at 11:18

If what reported in the comment is relevant for the question, then what reported by the OP in the comment should be also be written in the question. The question should be clear to any reader, including who is just reading the question because has a similar problem; it should not be required to dig in the comments to understand what exactly it is being asked. That is more important when the comment left from the OP to make the question clearer is a comment for one of the answer; you cannot pretend readers read every comment left for every answer to understand what the question is exactly asking, or the details that make the difference.

Adding a note that the question will be changed is useful, as who answers is not notified when the question is changed; they could notice a question has been changed (which could mean the question has new answers, an existing answer has been edited, or the question itself has been edited), if they watch the list of questions on the front page, and see the question they answered popped-up in the front page. As far as I remember, that is true also for the OP, who is not otherwise notified when an existing answer has been changed.

For this reason, I would not edit a post without leaving a comment. Keep in mind, anyway, that the OP is not notified when you leave a comment for the OP, but the OP didn't comment your answer. To notify him in that case, you should add a comment to the question.

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I appreciate your hint how to use comments to trigger an information to the questioner or answerer. I noticed that myself that the inbox notification is a really good help. –  mliebelt Dec 12 '11 at 6:35