I was reading a flyer for the 2010 Preston chess congress later this month, and saw there was a grading prize.  I haven't played an otb tournament in at least 5 years and have never seen/don't remember what they are. Even google didn't know!!

Could someone enlighten me?

A grading prize is where they award money to the player who performed the best out of any player in their grade. For example I recently played in a U1600 tournament in Milwaukee, and I have a 1300 rating, making me a class D player, and I scored more wins than all other D players in that tournament, so I got a grade prize of $50.

Thank you. :)