Tinea versicolor is a skin condition caused by an overgrowth of Malassezia, a type of yeast that naturally resides on the skin. When this yeast multiplies excessively, it disrupts the skin’s pigmentation, resulting in small, discolored patches that can be lighter or darker than the surrounding skin. These patches commonly appear on the chest, back, neck, and upper arms and may have a slight scaling or itching sensation.