Skin color is a conspicuous trait of biological and social importance. The associations of skin color with concepts of human races and social privilege in recent human history have added to the significance, as well as to the misunderstanding of the trait, in general society and in medicine. In this chapter, I present a short review of what we know about human skin color in its evolutionary and social contexts. Examination of the evolution of the diversity of skin color is an essential foundation because it informs our understanding of biological and social concepts of race, and of the validity of the concept of skin of color.