They used to be the epitome of casual living, but they’ve even been seen in the White House. Fashion designers sell versions of them that cost hundreds of U.S. Dollars. Formerly a humble form of footwear, flip flops have become a major fashion accessory.

The concept behind flip flops is simple. Most pairs consist of some kind of outsole with V-shaped straps sewn into the top, forming a thong at the peak. The wearer slips her feet between the straps, and the thong goes between the big toe and second toe. The shoe is kept on the foot by the wearer gripping the thong with the two toes as she walks. The name “flip flop” comes from the sound the shoes make as they slap against the wearer’s heel and then back on the ground.

Flip flops are the most common form of footwear in some developing countries. Their simple construction makes them cheap to manufacture, as well as to purchase. In some countries, flip flops may be made of cheap rubber, even by recycling automobile tires, which brings their price down further. Flip flops probably developed from the Japanese zori, the traditional shoe for women. They are known as “jandals” in some countries, a slang term from “Japanese sandals.”

Flip flops became popular in the West after World War II, when servicemen brought back zori as souvenirs and found that the shoes made convenient slippers. They were first mass produced in the United States around 1960, and they caught on quickly. Because of their construction, they are popular beach wear. They are also popular, in a rubberized form, in public showers, where they help prevent the transmission of foot fungi. Flip flops may be constructed of plastic urethane, leather, rubber and many other materials.

In the past ten years or so, flip flops have become fashionable. No longer just for the beach or a hot summer day, flip flops were suddenly on the Paris runways. Now they are seen everywhere in the U.S., from the beaches to formal dances. Designers have changed the materials, but have kept the basic form, so it is not unusual to see young ladies dressed for the prom wearing sparkly flip flops instead of dyed-to-match pumps. There are even forms of bridal flip flops for casual or beach weddings, or for the bride to wear at the wedding reception, instead of heels.

Clearly, flip flops have become acceptable footwear in most places. Some businesses may frown on their employees wearing these casual shoes, but they are popular for both men and women from all walks of life. Flip flops have come full circle from their Japanese origins to become fashionable footwear worldwide.