Swinging, believe it or not, was one of the earliest forms of sexual expression, dating back to ancient times in such places as Egypt, Iran, Asian countries. Having more than one lover was quite common. The Puritans and Christians since ancient times have been the ones to frown upon such practices. The swinging lifestyle of ancient times was not as structured as we see it today. Around the 1940's certain groups, who preferring not get divorced opted for the swinging practice to gain sexual pleasures. It wasn't until the 1950's that swinger personals cropped up and that terminology remains to this day. With the swinging lifestyle came parties, private parties, off premise and on premise gatherings, tours, vacations, clubs, personal ads, cruises, weekend getaways.
Because this sexual lifestyle has not been acceptable by society at large, a large percentage of swingers are still in the closet.