Degree of difficulty (DD, sometimes called tariff or grade) is a concept used in several sports and other competitions to indicate the technical difficulty of a skill, performance, or course, often as a factor in scoring.[1] Sports which incorporate a degree of difficulty in scoring include bouldering, cross-country skiing, diving, equestrianism, figure skating, freestyle skiing, gymnastics, rhythmic gymnastics, surfing, synchronized swimming and trampoline. Degree of difficulty is typically intended to be an objective measure, in sports whose scoring may also rely on subjective judgments of performance.