Well You Must Check FAQ Section or Make a Manual Research on Why Such Things Are Commonly Used on Boards.
As Said by glengainer - It's Only a Reputation Power. Some one Increases Your Reputations If He/She Likes Your Contribution/Share. Also Remember, You Cannot Forcefully Ask Someone To Increase Your Rep Power.
Below is a Button Highlighted Wherein You Can Find Out How You Can Increase Someone Else's Reputation.
