A bikini or two-piece is a type of women's swimsuit, characterize by two separate parts — one covering the breasts, the other the groin (and optionally the buttocks), leaving an uncovered area between the two garments. It is often worn in hot weather and while swimming. The shapes of both parts of a bikini closely resemble women's underwear, and the lower part of a bikini can therefore range from the more revealing thong or g-string to briefs and the more modest square-cut shorts.