Why are some comments deleted?

Comments are intended as secondary notes on statements and answers.

A deleted comment is only visible to its author and to moderators. It can still be voted, but can no longer be flagged.

The decision to delete a comment stems from a flag for one of these reasons:

• The comment is spam, meaning it advertises a product or a service.
• The comment contains obscenities, insults or any other messages that have no useful content (for example qwqweqwqeeqwe).
• The comment is unnecessary: it has been merged into the message, it is out of date or no longer relevant to this article.
• Other reasons: when a reviewer votes to delete the comment, Dignitas encourages him or her to briefly motivate his or her decision.

Also, the comment's author and the moderators can delete it.