Louis Réard, a French car engineer who was running his mother's lingerie shop in Paris, introduced two small pieces of clothing and advertised them as "the smallest bathing suit in the world."
Simultaneously, fashion designer Jacques Heim was working on a similar design. He called his the Atome (French for Atom)
Réard named his invention the bikini because of the Bikini Atoll nuclear tests. He thought that everyone would be shocked by the risqué display of curves and belly buttons. The joke at the time was that that the 'bikini split the atom'.
The bikini came to the US in 1947, but was not seen much in public until about 1960. In 1964 Sport’s Illustrated published its first Swimsuit Edition.
The real origin of the Bikini can be found in the above mosaic discovered in Sicily. Its thousands of colored tiles show women in bikinis playing and exercising by the beach.
Incidentally, in 1932, one of the first men's chest-revealing swimsuits, the “Topper,” was introduced. It boasted a detachable top that could be zipped away from the trunk bottoms. Many men chose to go topless in this swimsuit and were arrested for indecent exposure.