Foot, athlete
A skin infection caused by a fungus called Trichophyton which can thrive and infect the upper layer of the skin when the feet (or other areas of the body) remain moist, warm, and irritated.
The fungus can be found on floors and in socks and clothing and can be spread from person to person by contact with these objects.
However, without proper growing conditions (a warm, moist environment), the fungus will not infect the skin.