Racial segregation is the separation of people into racial or other ethnic groups in daily life. Segregation can involve the spatial separation of the races, and mandatory use of different institutions, such as schools and hospitals by people of different races. Specifically, it may be applied to activities such as eating in restaurants, drinking from water fountains, using public toilets, attending schools, going to movie theaters, riding buses, renting or purchasing homes, renting hotel rooms, going to supermarkets, or attending places of worship. In addition, segregation often allows close contact between members of different racial or ethnic groups in hierarchical situations, such as allowing a person of one race to work as a servant for a member of another race. Racial segregation has generally been outlawed worldwide.

Segregation is defined by the European Commission against Racism and Intolerance as "the act by which a (natural or legal) person separates other persons on the basis of one of the enumerated grounds without an objective and reasonable justification, in conformity with the proposed definition of discrimination. As a result, the voluntary act of separating oneself from other people on the basis of one of the enumerated grounds does not constitute segregation". According to the UN Forum on Minority Issues, "The creation and development of classes and schools providing education in minority languages should not be considered impermissible segregation if the assignment to such classes and schools is of a voluntary nature." Racial segregation can amount to the international crime of apartheid and a crime against humanity under the 2002 Rome Declaration of Statute of the International Criminal Court.

Historic cases from ancient times to the 1960s

Racial segregation was often used to secure the advantages enjoyed by a certain dominant group, e.g. "various conquerors—among them Asian Mongols, African Bantu, and American Aztecs".