What is Slope and Rating?

The USGA website explains both slope and rating as a way to measure the difficulty level of a golf course. For course rating the website says

“Course Rating is the evaluation of the playing difficulty of a course for scratch golfers based on yardage and other obstacles to the extent that the affect the scoring difficulty of the scratch golfer.”

While

“Slope Rating is measurement of the relative difficulty for the bogey golfer compared to the course rating. The lowest slope is 55 and the highest slope is 155.”

For more information check out the USGA website on Course Rating and Slope Rating.