A relief option that lets a player drop a ball anywhere along the straight line running from the hole through the spot where the original ball lay, as far back on that line as they like. Once the ball is dropped and first touches the ground, it creates a relief area one club-length in any direction from that spot, and the ball must come to rest in it, not nearer the hole. It's available for an unplayable ball anywhere except a penalty area (Rule 19.2b) and for a ball in a red or yellow penalty area (Rule 17), always for one penalty stroke. Going straight back to short grass, even if it lengthens the approach, is often the safer play than a lateral drop that stays in trouble.