Racism refers to the beliefs and practices that assume inherent and significant differences exist between the genetics of various groups of human beings; that assume these differences can be measured on a scale of "superior" to "inferior"; and that result in the social, political and economic advantage of one group in relation to others.
In general, a racist practices the separation of groups according to race, and considers one's own race the most valuable and others less valuable. The belief that the character and abilities of individuals are correlated with their race is not necessarily racism, since this can be asserted without implying an inequality in value. The application of this belief in dealing with members of that race, especially with little regard for variations within "races", is known as racial prejudice. Granting or withholding rights or privileges based on race or refusing to associate with persons based on race is racial discrimination.
Racism has historically been defined as the belief that race is the primary determinant of human capacities, that a certain race is inherently superior or inferior to others, and/or that individuals should be treated differently according to their racial designation. Sometimes racism means beliefs, practices, and institutions that discriminate against people based on their perceived or ascribed race. There is a growing, but somewhat controversial, opinion that racism is a system of oppression -- a nexus of racist beliefs, whether explicit, tacit or unconscious; practices; organizations and institutions that combine to discriminate against and societally marginalize a class of people who share a common racial designation, based on that designation.
Some believe that the term also is often used incorrectly by supporters of cultural relativism and political correctness to stigmatise their adversaries due to the association between racism and extreme violence in parts of the twentieth century.
Since the last quarter of the 20th century, there have been few in developed nations who describe themselves as racist, so that identification of a group or person as racist is nearly always controversial. Racism is regarded by many as an affront to basic human dignity and a violation of human rights. A number of international treaties have sought to end racism. The United Nations uses a definition of racist discrimination laid out in the International Convention on the Elimination of All Forms of Racial Discrimination and adopted in 1966:
...any distinction, exclusion, restriction or preference based on race, colour, descent, or national or ethnic origin which has the purpose or effect of nullifying or impairing the recognition, enjoyment or exercise, on an equal footing, of human rights and fundamental freedoms in the political, economic, social, cultural or any other field of public life.