Undergarments are clothes worn under other clothes, often directly next to the skin, but may comprise more than one layer. They keep outer garments from being soiled by bodily secretions and discharges, shape the body, and provide support for parts of it. In cold weather, long underwear is sometimes worn to provide additional warmth. Special types of undergarments have religious significance. Some items of clothing are designed as undergarments, while others, such as T-shirts and certain types of shorts, are appropriate both as undergarments and as outer clothing. If made of suitable material, some undergarments can serve as nightwear or swimsuits, and some are intended for erotic effect.