Tinea versicolor is a fungal infection of the skin. It's also called pityriasis versicolor and is caused by a type of yeast that naturally lives on your skin. When the yeast grows out of control, the skin disease, which appears as a rash, is the result.
The infection can happen for any of the following reasons:
You have oily skin
You live in a hot climate
You sweat a lot
You have a weak immune system
Because the yeast grows naturally on your skin, tinea versicolor is not contagious...