Ringworm, also known as "Tinea", is a contagious fungal infection of the skin, and can exist anywhere on the body. Contrary to its name, ringworm is not caused by a worm, but generally is a reddish to brownish raised or bumpy patch of skin that may be lighter in the center, giving the appearance of a 'ring'.
Fungi are tiny organisms that survive by eating plant or animal material. The ringworm fungi feed on keratin, the material found in the outer layer of skin, hair, and nails. These fungi thrive best on skin that is moist, hot, and hidden from the light. When this infection is found on the feet, it is commonly called athlete's foot; when it is found in the groin it is commonly called jock itch; and when it is found on the body it is still called ringworm. Up to 20 percent of the population has one of these infections at any given moment.citation needed]