When skin pigmentation as a characteristic of race becomes significant in some way, this phenomenon is known as racialism. Many people and societies overlay racialism with racist perceptions and systems which arbitrarily assign to groups of people a status of inherent superiority or inferiority, privilege or disadvantage based on skin color or racial classification. Apartheid-era South Africa is an example of a white supremacist society based on a system of stratification of power and privilege by skin color, as well as racial admixture. Similar examples can be found in Brazil's highly socially color-stratified society; and, in the U.S., segregation and institutional racism on the part of white-controlled and black-controlled institutions, and internal "color consciousness" on the part of some ethnic minorities. Prejudice against people with more highly pigmented skin is the most pervasive form of color bias. Many other societies remain informally divided on the basis of skin color and, often, related ethnicity. (See also colonialism, Nazism, pigmentocracy and institutional racism.)
Various presumptions about people with regard to hair color are far less common than skin-color bias, have far fewer and less serious real-world implications, and are more often applied to women than to men. Common stereotypes in the West are dumb blondes, hot-tempered redheads and vixen brunettes.
