Leotards are one-piece clothing garments that were originally developed for male acrobats, although bathing suits can also be one-piece clothing garments that are meant for women. Leotards are usually made of lycra (a synthetic fiber that is lightweight and flexible) or spandex (a type of lycra), while one-pieces are generally made out of swimsuit material. Lycra is a generic name for a group of polymers invented by DuPont in 1975. There are several different types of Lycra, including elastane. Elastane is a natural product derived from trees and it's used to create stretchy fabrics that will hold their shape when you bend or compress them. Spandex is a brand name for a type of Lycra used in clothing and other products. Like Lycra, Spandex is a synthetic fiber that was originally developed for use in acrobat costumes but has been widely adopted by the fashion industry as a comfortable, stylish garment material. So, leotards are worn over pants or shorts, whereas one-pieces are worn directly under a shirt or sweater. There are three main parts to a leotard: the top, the waistband, and the leg openings.