Athlete’s foot is caused by an infection of a fungus, which is a type of microscopic organism similar to bacteria and viruses. This infection enters the body through small cracks and defects in the skin and often occurs in environments where fungus thrives the most, including the moist surfaces of bathrooms, showers, and locker rooms. The fungus irritates the skin as it multiplies during the infection, and creates peeling of the skin, redness, itching, and burning pain. The fungus often invades the tissue on the bottom of the foot and a between the toes, but sometimes it can invade the top of the foot, where the infection is known as ringworm. The fungus can also invade the skin under the toenails, leading to a toenail fungus infection.