The colour of a person's skin can range in tone from very light (a pinkish tone that is considered white) to very dark (black). This coloring is determined by the amount of melanin (a type of pigmentation) that is found in the skin. The amount of pigmentation that you have is determined by your ancestors and your sex. Males have slightly more pigmentation than females no matter what their skin colour or heritage.
Most people take skin pigmentation for granted. No matter what colour their skin is it is usually fairly regular in shade and tone. However, certain conditions and factors do exist that can cause skin pigmentation changes.