Most people’s feet have a gap where the inner part of their foot (the arch) is raised off the ground when they stand. The height of this arch varies.
Some people’s feet, however, have a low arch or no arch at all, which is referred to as flat feet or fallen arches.
When someone with flat feet stands, their inner foot or arch flattens, and the foot may roll over to the inner side (known as over-pronation).
Some people with flat feet never have any trouble or pain. Others may suffer from aching feet, or find that it puts a strain on the connecting ligaments and muscles, which causes pain in the leg joints when walking.
Continue to next section: Symptoms of flat feet