[GreaterFool]

Downvoting on HN confuses me. I don't ever downvote anything, I think it's a bad idea. Upvoting is ok, downvoting should be removed.

Also, looking at comments, often I see only upvote and no downvote button. Why is that?

[detaro]

You can only downvote during the first 24 hours, and only comments that are not replies to you.