Horse and rider complete a series of tests
The rider must show complete control over the horse by getting it to perform a number of movements, and a panel of judges awards marks for the execution.
The horse is taken through a series of tests, such as the pirouette, piaffe and passage, in a walk, trot and canter.
It must be energetic yet calm, strong yet submissive to the rider, and precise in its movements.
The scoring for dressage is relatively complicated.
The five judges each score a move from 0 to 10, with 10 being the highest mark on offer.
The more difficult movements can earn scores that are doubled, and judges also give a collective mark for the aesthetic quality of the performance.
In the Olympics the first round is a Grand Prix test, which also doubles as the team competition.
The team event is decided after the first round, based upon the three best individual scores from each team.
The riders follow a set routine of movements and the best 25 go forward to the next round, called the Grand Prix Special.
The best 15 from that round go into the final, known as the Grand Prix Freestyle or the Kur.
In the Kur riders perform a routine they have devised themselves, using music they have chosen, which must last no longer than six minutes.