Class discrimination, also known as classism, is prejudice or discrimination on the basis of social class. It includes individual attitudes, behaviors, systems of policies, and practices that are set up to benefit the upper class at the expense of the lower class.
For example, middle-class and upper-class individuals in the U.S. referring to working class, white Americans as "poor white trash" can be regarded as a form of class prejudice, the insult having the capacity to be historically analogous to racist language against African-Americans.
Class structures existed in a simplified form in pre-agricultural societies, but became much more complex and established following the establishment of permanent agriculture-based civilizations with a food surplus. Classism started to be practiced around the 18th century.
The term classism can refer to personal prejudice against lower or upper classes as well as to institutional classism, just as the term racism can refer either strictly to personal prejudice or to institutional racism. The former has been defined as "the ways in which conscious or unconscious classism is manifest in the various institutions of our society."
The term "interpersonal" is sometimes used in place of "personal" as in, "institutional classism (versus) interpersonal classism.", and terms such as "attitude" or "attitudinal" may replaced "interpersonal" as contrasting with institutional classism, as in the Association of Magazine Media's definition of classism as "any attitude or institutional practice which subordinates people due to income, occupation, education and/or their economic condition."
Classism is also sometimes broken down into more than two categories, as in "personal, institutional and cultural" classism.