History suggests that fearless woman dating back as far as the ancient roman times were wearing two piece suits during athletic occasions as etched in the famous Villa Romana del Casale and yet it wasn't until Jacques Heim debuted a two piece suit now known as the bikini titled "Atome" in May of 1946 and caught the attention of a young Louis Reard a mechanical engineer who had taken over his mother's lingerie shop was inspired after a trip to St Tropez where he noticed women rolling and adjusting their swimsuits to get a better tan that the "Bikini" seemed to gain some momentum. 
Reard quickly created his own take on the string bikini consisting of 4 triangles of 30cm material in the now iconic newspaper print. Yep the first ever bikini print was of Newspaper Headlines! The bikini was such a hit Reard received over 50,000 fan letters! And continued to sell his designs in Paris for over 40 years.
"The bikini gradually grew to gain wide acceptance in Western society. According to French fashion historian Olivier Saillard, the bikini is perhaps the most popular type of female beachwear around the globe because of "the power of women, and not the power of fashion". As he explains, "The emancipation of swimwear has always been linked to the emancipation of women." By the early 2000s, bikinis had become a US$811 million business annually, and boosted spin-off services like bikini waxing and the sun tanning."
Bikini Trends
1940's: The birth of the Bikini and for the first time women are baring their midriffs for the world to see. Ground breaking. Halter Neck styles that promote the sexy corset style was the first bikini of choice. 
1950's: Hollywood Star's Bidgette Bardot and Esther Williams make history on French beaches when they are in town for the Cannes Film Festival by wearing the revealing creations. Causing magazine publications to label the bikini and its wearers" tactless and without decency"
1960's: It's the swinging 60's and Bryan Hyland singing about bikinis on the radio: "Itsy Bitsy Teenie Weenie Yellow Polka Dot Bikini." is a hit song.  Two years later, Ursula Andress emerges from the sea wearing a belted white bikini (ICONIC) as Honey Ryder in Dr. No, Sean Connery's first James Bond film. That same year, Playboyfinally puts a bikini on the cover. 
1970's: 70s were all about high waisted bottoms and barely any coverage. Without any restrictions, designers used this time to experiment with different styles and reveal nearly every curve of the female figure. The Beach Boys are writing songs like "California Girls" and "Surfin' Safari," and surf culture became deeply intertwined in the bikini culture.
1980's: Christie Brinkley graces the cover of the Sports Illustrated Swimsuit edition 3 years in a row. Neon colors, scoop necks, V-hips all became swimwear trends in the 80's. Speedo style swimsuits that were made of nylon/elastane became the new fabric of choice in the eighties and still remain the number one fabric today for women’s swimwear. Full piece bathing suits produced by brands like speedo and body glove began to make their popularity in the 80’s that were cut to look like athletic style suits. High rise bikini bottoms and scoop necks with a built-in bra support for movement and speed. Notable mention to Bo Derek who also made braids and a bikini iconic of that era.
1990's: Ellle Mcpherson is "THE BODY". The suit grows smaller than ever, as G-strings make their way north from Brazil and suits are cut higher than ever at the thigh. They also had the bikini tops with adjustable straps, almost as if they were bras. Baywatch is born and with it Pam Anderson and "that red bikini" 
2000's:  The era of the ultra fit celeb. Everyone has got a bikini bod and they are showing it. Think one pieces with sexy cut out details worn with giant slogan sunglasses. Beyonce owns the 2000's and bikinis are now seen as common place from runways to the riviera.
Current: Our current state has seen the rise of the "minimalist" bikini brands. Some do it amazing and some not so much. What is lost in design detail is made up in high end luxe fabrics with luxe features such as heat bonded fabrics and anti rash weaves.
Long Live the BIKINI!