The body normally hosts a variety of microorganisms, including bacteria, mold-like fungi (dermatophytes), and yeast-like fungi (such as Candida). Some of these are useful to the body. Others may multiply rapidly and cause symptoms.

Tinea corporis (often called ringworm of the body) is a common skin disorder, especially among children, but it may occur in people of all ages. It is caused by mold-like fungi (dermatophytes). See also tinea capitis (involving the scalp), tinea cruris (jock itch), and tinea pedis (athlete's foot).

Fungi thrive in warm, moist areas. Susceptibility to fungal infection is increased by poor hygiene, prolonged wetness of the skin (such as from sweating), and minor skin or nail injuries.

Tinea infections are contagious and can be passed by direct contact with affected individuals or by contact with contaminated items such as combs, clothing, shower, or pool surfaces. They can also be transmitted by contact with pets that carry the fungus (cats are common carriers).