The main causes of skin pigmentation are believed to be allergies and sun exposure. Your genetic makeup greatly influences whether you are predisposed to skin pigmentation or not. Skin darkening is referred to as "pigmentation." Melanin is a chemical that is produced by our skin. It is this component that gives skin its natural hue. The likelihood of developing darker skin increases if your skin generates more melanin. Basically, there are two different forms of skin pigmentation: hyper and hypo pigmentation.