Shadism, a legacy of slavery, is a form of skin tone bias that identifies groups and individuals on the basis of their degree of pigmentation.

It is an evaluation of people that minutely registers traits such as skin color, hair, and facial features in order to construct social hierarchies.

For example, in the context of social apartheid in Brazil, and elsewhere in Latin America, people with pale skin, tall stature, light eyes, dark and very straight or light and straight or wavy hair, and aquiline noses are considered more beautiful, powerful, influent and good-natured than people of European and Middle Eastern descent with other phenotypes, and those are of greater status than lower and middle class people of Asian descent in social hierarchy, which also gives preference to multiracials (Pardos, mestizos, etc.) whose features more closely touches the idealized Northern and Western Europeans in comparison to those whose facial features, hair texture and skin color more resemble the Africans, or whose facial features and stature more resemble Amerindians, the latter associated with savagery, uneducation and superstitions.

The term black people is used in some socially-based systems of racial classification for humans of a dark-skinned phenotype, relative to other racial groups represented in a particular social context. Different societies apply different criteria regarding who is classified as "black", and often social variables such as class and socio-economic status also play a role, so that relatively dark-skinned people can be classified as white if they fulfill other social criteria of "whiteness" and relatively light-skinned people can be classified as black if they fulfill the social criteria for "blackness" in a particular setting.

As a biological phenotype being "black" is often associated with the very dark skin colors of some people who are classified as "black". But, particularly in the United States, the racial or ethnic classification also refers to people with all possible kinds of skin pigmentation from the darkest through to the very lightest skin colors, including albinos, if they are believed by others to have African ancestry, or to exhibit cultural traits associated with being "African-American". As a result, in the United States the term "black people" is not an indicator of skin color but of socially based racial classification.