Hacker News currently has one full-time moderator: Dan Gackle (dang), and formerly Scott Bell (sctb). Their comment replies provide a pseudo-log of Hacker News moderation.
Dan is very responsive when contacted at firstname.lastname@example.org, and is the best option for resolving any issues on Hacker News.
Downvoting comments. (via github.com)
All comments start with a score of 1 point (but in order to prevent bandwagoning, the comment score is not visible to users other than the author). After users reach 501 Karma, they gain the ability to downvote another comment.
Downvoted comments (i.e. with a score
You cannot downvote comments which are direct replies to your own comment, and you cannot downvote 24 hours after the original comment was made.
If a user has 31 Karma, they can flag submissions. Although submissions cannot be downvoted, flags act as a "super" downvote, and enough flags will strongly reduce the rank of the submission, or kill it entirely (flagging is supposed to be used for submissions that break the site guidelines, but that isn't always the case in practice). A submission that's flagged to death will have a [flagged] tag. Comments behave similarly.
A [dead] submission (that does not also show [flagged]) is killed by a moderator or by the software. They will only be shown to users who have shown dead enabled in their profiles. A submission can simultaneously be [flagged] and [dead].
If a user has 31 Karma, they can also vouch for a [dead] submission/comment. A vouched submission/comment has its rank restored (and potentially improved as the vouch can counteract the effects of flags), but it can be [dead] again at which point it can't be re-vouched.
Setting top color
If a user has 251 Karma, they can set the color of the top bar in their profile settings. The default is #ff6600. Here's the complete set of colors users have set.
The FAQ states "users should vote for a story because they personally find it intellectually interesting, not because someone has content to promote." Indeed, Hacker News utilizes a voting ring detector that will prevent caught submissions from hitting the front page. Due to sites like Product Hunt normalizing the asking for upvotes or other engagement via social media, the implicit asking of upvotes is also done for Hacker News, usually due to ignorance of the Hacker News rule against it. There are very few good reasons to draw attention to a Hacker News submission immediately after it has been submitted.
One popular "trick" for obfuscating voting manipulation on Hacker News is to link to the Hacker News's /newest page of new submissions (instead of a direct link which would otherwise make voting manipulation obvious), and asking friends to upvote the submission from that page. This trick doesn't actually work.
The FAQ notes that submission rank is impacted by "software which down weights overheated discussions." A good rule of thumb for this effect is when the number of comments on a submission exceeds its score.
Moderators can overrule the downranking for appropriate, not-actually-a-flame-war discussions.