A bikini is typically a women's two-piece swimsuit featuring two triangles of fabric on top, similar to a bra and covering the woman's breasts, and two triangles of fabric on the bottom, the front covering the pelvisbut exposing the navel, and the back covering the buttocks. The size of the top and bottom can vary from full coverage of the breasts, pelvis, and buttocks, to very skimpy designs like a thong or G-string that cover only the areolae and mons pubis, but expose the buttocks.
A one-piece swimsuit most commonly refers to swimwear worn by women and girls when swimming in the sea or in a swimming pool, or for any activity in the sun, such as sun bathing. Today, the one-piece swimsuit is usually a skin-tight garment that covers a female's torso, except maybe the back or upper chest.
The tankini is a bathing suit combining a tank top, mostly made of spandex-and-cotton or Lycra-and-nylon, and a bikini bottom introduced in the late 1990s. This type of swimwear is considered by some to provide modesty closer to a one-piece suit with the convenience of a two-piece suit, as the entire suit need not be removed in order to use a toilet. Tankinis come in a variety of styles, colors and shapes, some include features such as integrated push-up bras. It is particularly popular as children's beachwear, and athletic outfit good enough for a triathlon.
The monokini, designed by Rudi Gernreich in 1964, consisting of only a brief, close-fitting bottom and two thin straps, was the first women's topless swimsuit. His revolutionary and controversial design included a bottom that "extended from the midriff to the upper thigh" and was "held up by shoestring laces that make a halter around the neck."Some credit Gernreich's design with initiating,or describe it as a symbol of, the sexual revolution.
Some manufacturers and retailers refer to modern monokini swimsuit designs as a topless swimsuit, topless bikini, or unikini.