I tend to upvote a post when it Links an interesting article or provokes an interesting conversation, and only downvote them when they voice an convectively bad opinion (like, bigotry or other unjustified vitriol).
I tend to upvote comments when they make a good point or at least try to support their argument, and only downvote them for the same reason as posts: when they are trolling, being unnecessarily aggressive, or trying to justify bigotry with fallacious reasoning or something
What about you?
They represent the general opinion of the community.
What else is it supposed to mean?
You mean it does not result in something like karma points.