A hazard is an area of a golf course in the sport of golf which provides a difficult obstacle, which may be of two types: (1) water hazards such as lakes and rivers; and (2) man-made hazards such as bunkers. Special rules apply to playing balls that fall in a hazard. For example, a player may not touch the ground with his club before playing a ball, not even for a practice swing. A ball in any hazard may be played as it lies without penalty. If it cannot be played from the hazard, the ball may be hit from another location, generally with a penalty of one stroke. The Rules of Golf govern exactly from where the ball may be played outside a hazard. Bunkers (or sand traps) are shallow pits filled with sand and generally incorporating a raised lip or barrier, from which the ball is more difficult to play than from grass.