Golfers post scores on GHIN.com, which is a handicap computation service provided by the United States Golf Association. The USGA provides this service to over 12,000 golf clubs and approximately 2.3 million golfers as of 2015. In order to use the GHIN.com system to post a score, the golfer must obtain a GHIN number from an authorized golf club. Once he has that number, he can enter his 18-hole score either on the website or GHIN's mobile app.
The system computes an indexed handicap so that golfers of different abilities can play together and fairly compete. A golfer's indexed handicap changes as he posts scores and plays on courses of varying difficulty.
Golfers can also look up their current handicap at the website by entering their GHIN number. A golfer can also view his last 20 scores on which the handicap was computed. In order to utilize the GHIN system, a club must be a member of its state or regional golf association.
The USGA also rates golf courses; these ratings are available on the Association's website and can help a player determine the difficulty of the course and the tees from which he should play. After entering the club name and location, the golfer has access to a few different ratings for that club. Unless the golfer is a scratch player, he should review the Bogey rating for the course before deciding from which tees to play.