Lycra, also known as spandex, is a synthetic fiber that is used in a variety of clothing items. It is known for its elasticity and strength, making it an ideal material for garments that require a lot of stretching and movement. It is often used in swimwear, activewear, and lingerie, as well as in some types of formal wear. Lycra is also used in the production of medical compression garments, such as those used to treat lymphedema.