Somewhat comparable to a human triathlon, the discipline of eventing was historically developed to test the skills required of the working military mount--athleticism, agility, bravery, speed, and endurance.
In modern times, eventing has evolved into an exciting spectator sport and competitive endeavor attracting enthusiasts of all levels--from weekend amateur riders to international professionals. At its highest level, eventing is recognized as one of the three Olympic equestrian disciplines, but is also offers activities and competitions for riders and horses of all levels.
Eventing is divided into three phases: dressage, cross-country, and show jumping. These phases of the competition are usually held over the course of three days, hence the other popular term for this discipline, the three-day event.
Dressage is held the first day to demonstrate the level of communication between horse and rider and showcase the horse's power, balance, rhythm, and suppleness which are tested further in the following two phases.
The second day of the event entails the cross-country test in which the endurance, jumping ability, and speed is tested as horse and rider negotiate a course of fixed obstacles set on varied terrain usually measuring between 2.75 to 4 miles.
The third and final phase, show jumping, tests the horse's suppleness, obedience, and stamina after two prior days of exertion, and also the rider's precision and accuracy as the horse/rider team negotiate a set course of strategically placed obstacles within the confines of an arena.
Information provided by the U.S. EQUESTRIAN FEDERATION