All golf courses are rated to allow players to take their Handicap Indexes to any course in the world and be able to compete on an equal level with other golfers. This allows a player to receive enough handicap strokes to play at an equal level of any other golfer, even when an opponent is a scratch player. Without ratings, it would not be possible to post scores for handicap purposes or maintain the Handicap Index.
The course rating procedure is performed to determine the difficulty of playing on the course in average, normal conditions. Rating process is described precisely in the USGA Course Rating System™ manual. Procedure includes determining of effective playing length of all holes as well as measuring the fairways, inspecting the bunkers, measuring the size and contours of the greens, determining the distance to hazards and out of bounds locations, etc. After rating the obstacles, the rating team plays the golf course to gain greater insight, from a player perspective, and to clarify any doubts or questions that may arise on specific holes or shots.
When the course is rated, two numerical value are both determined from each set of tees. These numbers are called Course Rating and Slope Rating.
The Course Rating (CR) is a number, close to par for the course, that indicates the difficulty of a golf course for a scratch player (0 Handicap Index) under average course conditions and normal weather. CR is expressed as a number with a single decimal digit, for example 71,8.
The Slope Rating (SR) is a number that represents the relative difficulty of a course for players who are not scratch players compared to scratch players. Slope Rating is expressed as a integer between 55 and 155. A course of standard playing difficulty have a rating of 113.
The values of Course Rating and Slope Rating are used to convert a Handicap Index into a Course Handicap, which indicates the number of handicap strokes for a given round of a golfer from a given set of tees.
more about Course Handicap …
The Course Rating and the Slope Rating typically are printed on the scorecard for a golf course. They are also available at many webpages.
For example if rating teams use USGA software the current data are available in USGA Course Rating and Slope Database™.
update: November 2020