Equestrianism refers to the skill of riding or driving horses. This broad description includes both use of horses for practical, working purposes as well as recreational activities and competitive sports. Horses are trained and ridden for practical working purposes such as in police work or for controlling herd animals on a ranch. They are also used in competitive sports such as dressage, endurance racing, eventing, horseball, reining, show jumping, tent pegging, vaulting, polo, horse racing, puissance and rodeo. Other popular forms of competition are grouped together at horse shows, where horse perform in a wide variety of disciplines. Horses (and other equids such as mules and donkeys) are used for non-competitive recreational riding such as fox hunting, trail riding or hacking. There is public access to horse trails in almost every part of the world; many parks, ranches, and barns offer both guided and independent trail riding. Horses are also ridden for therapeutic purposes, both in specialized paraequestrian competition as well as non-competitive riding to improve human health and emotional development.