Undershirts, also known as tees, are a type of clothing worn underneath other garments. They are typically made of lightweight fabrics such as cotton and are designed to be comfortable and breathable. They are usually short-sleeved and have a crew neckline. Undershirts are often used to provide an extra layer of warmth in cold weather, or to absorb sweat and keep the outer garment clean. They can also be used to add a layer of modesty when wearing more revealing clothing.