This document discusses the concepts of ethnicity, race, nationality, and ethnic groups. It defines ethnicity as people who share cultural identity or heritage, race as people who share biological ancestry, and nationality as people who share legal attachment to a country. Ethnic groups may be defined by traits like religion, culture, or shared history. The document also discusses how ethnic groups form through immigration and indigenous populations, and the concepts of acculturation, assimilation, ethnic neighborhoods, and ghettos.