The term race or racial group usually refers to the categorisation of humans into populations or groups on the basis of various sets of heritable characteristics. The physical features commonly seen as indicating race are salient visual traits such as skin colour, cranial or facial features and hair texture. Consequently, an ethnic group is a group of humans whose members identify with each other, through a common heritage that is real or assumed. Ethnic identity is further marked in the recognition from others of a group's distinctiveness and the recognition of common cultural, linguistic, religious, behavioural traits as indicators of contrast to other groups. Ethnicity is an important means through which people can identify themselves. This book presents and reviews important data on race and ethnicity.