Is it important to rate the responses?

You can rate more than just responses and comments right? You can even rate a random discussion in which you're not even involved. Why's that? And, what happens if you give a negative rating?

People don't know whether each of their individual responses have been rated. However if you like a response you should rate it as that means the person who wrote it will earn a little bit more from it. I think rating responses is a great way of rewarding your friends for taking the time to answer you.