The International Scale of River Difficulty is an American system used to rate the difficulty of a stretch of river, or a single (sometimes whitewater) rapid. The scale was created by the American Whitewater Association for the purpose of evaluating rivers throughout the world, hence International in the title. The grade reflects the technical difficulty and skill level required associated with the section of river. The scale is of use to various water sports and activities, such as rafting, riverboarding, whitewater canoeing, stand up paddle surfing, and whitewater kayaking.