African Americans (also referred to as Black Americans or Afro-Americans) are citizens or residents of the United States who have origins in any of the black populations of Africa.^[3] In the United States, the terms are generally used for Americans with at least partial Sub-Saharan African ancestry. Most African Americans are the direct descendants of captive Africans who survived the slavery era within the boundaries of the present United States, although some are—or are descended from—immigrants from African, Caribbean, Central American or South American nations.^[4] As an adjective, the term is usually spelled African-American.

http://en.wikipedia.org/wiki/African_americans