The lack of support provided by thong sandals is thought by some to be a major cause of injuries.
Some flip-flops have a spongy sole, causing the foot to roll further inward than normal when it hits the ground—an action called over-pronation, which is responsible for many foot problems.
In India, flip-flops are commonly known as hawai chappal.
Thong sandals have been worn for thousands of years, dating back to pictures of them in ancient Egyptian murals from 4,000 BC.
This style of footwear has been worn by the people of many cultures throughout the world, originating as early as the ancient Egyptians in 1,500 B. The modern flip-flop descends from the Japanese zōri, which became popular after World War II when soldiers returning to the United States brought them back.
They became popular unisex summer footwear starting in the 1960s.
The modern sandals are made of more modern materials, such as rubber, foam, plastic, leather, suede, and even fabric.