Bikini typically describes a women's simple 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 pelvis but 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 areola and mons pubis, but expose the buttocks.
Fashion designer Jacques Heim from Paris released a two-piece swimsuit design in 1946 that he named the Atome. Like swimsuits of the era, it covered the wearer's navel, and it failed to attract much attention. Parisian automotive engineer and designer Louis Réard introduced his design soon after. His skimpy design was risque, exposing the wearer's navel and much of her buttocks. No runway model would wear it, so he hired a nude dancer from the Casino de Paris to model it at a review of swimsuit fashions. He named the swimsuit after the Bikini Atoll, where the first public test of a nuclear bomb had taken place only four days before.