White supremacy is the belief, and promotion of the belief, that white people

White people

White people is a term which usually refers to human beings characterized, at least in part, by the light pigmentation of their skin...

 are superior to people of other racial backgrounds. The term is sometimes used specifically to describe a political ideology that advocates the social

Society

A society, or a human society, is a group of people related to each other through persistent relations, or a large social grouping sharing the same geographical or virtual territory, subject to the same political authority and dominant cultural expectations...

 and political

Politics

Politics is a process by which groups of people make collective decisions. The term is generally applied to the art or science of running governmental or state affairs, including behavior within civil governments, but also applies to institutions, fields, and special interest groups such as the...

 dominance by whites.
White supremacy, as with racial supremacism

Supremacism

Supremacism is the belief that a particular race, species, ethnic group, religion, gender, sexual orientation, belief system or culture is superior to others and entitles those who identify with it to dominate, control or rule those who do not.- Sexual :...

 in general, is rooted in ethnocentrism

Ethnocentrism

Ethnocentrism is the tendency to believe that one's ethnic or cultural group is centrally important, and that all other groups are measured in relation to one's own. The ethnocentric individual will judge other groups relative to his or her own particular ethnic group or culture, especially with...

 and a desire for hegemony

Hegemony

Hegemony is an indirect form of imperial dominance in which the hegemon rules sub-ordinate states by the implied means of power rather than direct military force. In Ancient Greece , hegemony denoted the politico–military dominance of a city-state over other city-states...

 and power,
and has frequently resulted in violence against non-whites.