The dressage tests performed at the Olympic Games are the highest level: Grand Prix.
Gaits and movements performed at this level include passage (a slow-motion, very elevated off the ground trot, pronounced like massage), and piaffe (the trot in place); one and two tempi changes at the canter where the horse appears to skip as it changes the leading leg in the canter, and canter pirouettes (a 360-degree circle, in place, at the canter).
Tests ridden at the Olympic Games are scored by a panel of five international judges. Olympic team medals are won by the teams with the highest, second highest, and third highest total percentage from their best three rides in the Grand Prix test. Once the team medals are determined, horses and riders compete for individual medals. The team competition serves as the first individual qualifier, in that the top 25 horse/rider combinations from the Grand Prix test move on to the next round. The second individual qualifier is the Grand Prix Special test, which consists of Grand Prix movements arranged in a different pattern. For those 25 riders, the scores from the Grand Prix and the Grand Prix Special are then combined and the resulting top 15 horse/rider combinations move on to the individual medal competition-the crowd-pleasing Grand Prix Freestyle.
For their freestyles, riders and horses perform specially choreographed patterns to music. At this level, the freestyle tests may contain all the Grand Prix movements, as well as double canter pirouettes, pirouettes in piaffe, and half-pass in passage. For the freestyle, judges award technical marks for the various movements, as well as artistic marks. In the case of a tie, the ride with the higher artistic marks wins.
For more information about the United States Equestrian Team, visit their website.