Show jumping is a part of a group of English riding equestrian events that also includes eventing, hunters, and equitation. Jumping classes are commonly seen at horse shows throughout the world, including the Olympics. Sometimes shows are limited exclusively to jumpers. Sometimes jumper classes are offered in conjunction with other English-style events. Sometimes, show jumping is but one division of a very large, all-breed competition that includes a very wide variety of disciplines. Jumping classes may be governed by various national horse show sanctioning organizations, such as the United States Equestrian Federation or the British Showjumping Association. International competitions are governed by the rules of the International Federation for Equestrian Sports. Hunters or jumpers Show jumping events have hunter classes, jumper classes and hunt seat equitation classes. Hunters are judged subjectively on the degree to which they meet an ideal standard of manners, style, and way of going. Conversely, jumper classes are scored objectively, based entirely on a numerical score determined only by whether the horse attempts the obstacle, clears it, and finishes the course in the allotted time. Jumper courses tend to be much more complex and technical than hunter courses because riders and horses are not being judged on style. Courses often are colorful and at times, quite creatively designed. Jumper courses can range anywhere in height from 0.80 meters to 1.60 meters. Hunters have meticulous turnout and tend toward very quiet, conservative horse tack and rider attire. Hunter bits, bridles, crops, spurs, and martingales are tightly regulated. Jumpers, while caring for their horses and grooming them well, are not scored on turnout, are allowed a wider range of equipment, and may wear less conservative attire, so long as it stays within the rules. Some events may make it compulsory to wear show jackets. Formal turnout always is preferred; a neat rider gives a good impression at shows. In addition to hunters and jumpers, there are equitation classes, sometimes called hunt seat equitation, which judges the ability of the rider. The equipment, clothing, and fence styles used in equitation more closely resemble hunter classes, although the technical difficulty of the courses may more closely resemble showjumping events. This is because both disciplines are designed to test the rider's ability to control the horse through a difficult course consisting of rollbacks, combinations, and higher obstacles. Rules Jumper classes are held over a course of show jumping obstacles, including verticals,