The colorful jackets that horse racing jockeys wear are referred to as silks. The name is derived from the silk material from which the jackets were originally made.
In modern times, the uniforms are primarily made of nylon taffeta, satin and lycra. A jockey's silks are often accompanied by a matching helmet, vest and gloves.
While those who bet on horse races tend to be superstitious, jockeys are equally superstitious about the color silks they wear during races. During certain races, jockeys prefer to wear certain colors because a higher percentages of racers have won races while wearing those colors. When jockeys are given or purchase a new uniform, they often throw it on the ground, stomp on it and soil it so as to ward off any similar misfortune during the race.