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Originally Posted by LeatherTrumpet

The term black people is an everyday English-language phrase, often used in socially-based systems of racial classification or of ethnicity to describe persons who are defined as belonging to a "black" ethnicity in their particular country, typically having a degree of Sub-Saharan African ancestry, or who are perceived to be dark-skinned relative to other "racial groups".

Different societies, such as Australia, Brazil, the United Kingdom, the United States and South Africa apply differing criteria regarding who is classified as "black", and these criteria have also varied over time. In some countries, social variables affect classification as much as skin-color, and the social criteria for "blackness" vary. For example, in North America the term black people is not necessarily an indicator of skin color or ethnic origin but is more of a socially-based racial classification related to being African American, with a family history related to institutionalized slavery. In South Africa, mixed-race people are not considered to be "black", and in other regions, such as Australia and Melanesia, the term "black" has been applied to, and used by, populations with a very different history.

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

These criteria have also varied over time

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