According to the USGA, every golf course receives both a USGA Course Rating® and USGA Slope Rating® for each set of tees that is rated. The rating established for the scratch golfer is known as the Course Rating. There is also a rating for the bogey player known as the Bogey Rating®.
This Bogey Rating is not normally published but is used to determine a Slope Rating. The Slope Rating is an evaluation of the relative difficulty of a course for players other than scratch. The USGA Course and Slope ratings are then calculated and certified by the authorized golf associations before they are issued to the club. These ratings are vital in calculating a person's handicap for that particular course (Course Handicap).
Learn more online on the USGA Web Site.