What is the meaning of "User has not selected a best response" in a Discussion?

@ANR2000 (135)
December 17, 2008 12:01pm CST
In the 1st post of Discussion there usually some thing like "User has not selected a best response." sentence, I wonder what it means? Also what happens when its been Selected? There is also this "Rate this discussion positive/negative" button in every response, What will be affected if i choose any of them?
1 response
@srijshm (1165)
• India
17 Dec 08
For me , it means that my reply still has a chance to get the the best response. I am also more inclined to post replies to such questions because being selected as the best response means extra rating & extra bucks. When i post a question, i make sure that after waiting for 3 days i always select the best response.
@ANR2000 (135)
• Indonesia
17 Dec 08
Thanx for the additional info, shonali didn't mention about "extra rating & extra bucks" for being selected XD But what about the "Rate this discussion ..." thing, what will it affects? is it reputation? or will it be something else?