Without rehashing [How long is an "Extended discussion"](https://law.meta.stackexchange.com/questions/892/how-long-is-an-extended-discussion) or [Should Moderators be able to use their privileges to benefit their own posts](https://law.meta.stackexchange.com/questions/896/should-moderators-be-able-to-use-their-privileges-to-benefit-their-own-posts), I am polling the community to establish a norm on this community for dealing with comments on questions and answers.

How do comments work?
---------------------

The comment [privilege](https://stackoverflow.com/help/privileges/comment) states:

> 
> **What are comments?**
> 
> 
> Comments are temporary "Post-It" notes left on a question or answer. They can be upvoted (but not downvoted) and flagged, but do not generate reputation. There's no revision history, and when they are deleted they're gone for good.
> 
> 
> **When should I comment?**
>  You should submit a comment if you want to:
> 
> 
> * Request clarification from the author;
> * Leave constructive criticism that guides the author in improving the post;
> * Add relevant but minor or transient information to a post (e.g. a link to a related question, or an alert to the author that the question has been updated).
> 
> 
> **When shouldn't I comment?**
> 
> 
> Comments are not recommended for any of the following:
> 
> 
> * Suggesting corrections that don't fundamentally change the meaning of the post; instead, make or suggest an edit;
> * Answering a question or providing an alternate solution to an existing answer; instead, post an actual answer (or edit to expand an existing one);
> * Compliments which do not add new information ("+1, great answer!"); instead, upvote it and pay it forward;
> * Criticisms which do not add anything constructive ("-1, see previous comments you scallywag!"); instead, downvote (and provide or upvote a better answer if appropriate);
> * Secondary discussion or debating a controversial point; please use chat instead;
> * Discussion of community behavior or site policies; please use meta instead.
> 
> 
> 

Further information is provided at a Stack Meta level (i.e. for all Stack Exchange sites) in [How do comments work?](https://meta.stackexchange.com/questions/19756/how-do-comments-work)

Relevantly:

> 
> Comments are often used to ask for clarification on, suggest corrections to, and provide meta-information about posts.
> 
> 
> Comments are disposable: unlike posts, there's no public revision history, and they can be deleted without warning by their authors, by moderators, and in response to flags.
> 
> 
> **Who can delete comments?**
> 
> 
> A user may delete one of their own comments at any time by clicking on the "Delete" button that appears to the right of the comment's timestamp when the comment is moused over.
> 
> 
> Comments that are flagged by multiple users are deleted automatically. The number of flags needed is usually based on the comment's score. It currently takes "3 + (Score / 3)" flags (rounded up) to delete a comment. Comments containing certain keywords can be deleted with a single flag.
> 
> 
> Moderators can delete any comment, or purge all comments from a post. They also have the ability to move all of a post's comments to chat.
> 
> 
> **When should comments be deleted?**
> 
> 
> Comments are temporary "Post-It" notes left on a question or answer. You should not expect them to be around forever. Once a clarification has been made, an edit added to the post to include new information, or the issue in the comment is otherwise resolved, it is subject to deletion. In reality, many obsolete or chatty comments remain untouched due to the high volume of comments posted, but this does not mean that they can't or shouldn't be deleted in the future.
> 
> 
> 

My view
-------

**Comments should be deleted once they have served their purpose**

The stated Stack Exchange intention for comments is to:

> 
> * Request clarification from the author;
> * Leave constructive criticism that guides the author in improving the post;
> * Add relevant but minor or transient information to a post (e.g. a link to a related question, or an alert to the author that the question has been updated).
> 
> 
> 

The first two of these are related in that they are a call to action for the OP to edit address the comment ideally by either by editing their post in response or considering the comment and deciding their post is fine without editing (possibly leaving a comment in reply) or, less ideally, by never bothering to do this. In any event, once the OP has done (or not done) something about it the comment has served its purpose and should be deleted, as should any too-and-fro comments that it prompted. 

Meta comments (such as a link to a related but not duplicate question) serve an ongoing purpose and should be left in perpetuity although, given that comments can be deleted at any time (and I don't know if they survive the deletion of the user) it may be better if this type of thing could be incorporated into the OP. I have seen this done and done it my self, crediting the poster of the the comment.

Of course, we also get comments that fall into the "When shouldn't I comment?" category. Users should be encouraged to do the action suggested instead and the comments should be deleted. Where they are of the "Secondary discussion or debating a controversial point" type they should be moved to chat as well.

As a practical matter, because users can only delete their own comments, comments for deletion need to be flagged for a mod. There is a canned "No longer needed" flag and requests to move to chat should use the "Something else" flag with a "move to chat" comment.

In addition, mods can decide that comments are no longer required by either 'cruising past' a question or by actively seeking out old comments through search tools.

However ...
-----------

If this community wants to treat comments differently than the Stack Exchange norm I am totally OK with that so:

**How to deal with comments?**