Racism is discrimination and prejudice against people based on their race or ethnicity. Racism can be present in social actions, practices, or political systems that support the expression of prejudice or aversion in discriminatory practices. The ideology underlying racist practices often assumes that humans can be subdivided into distinct groups that are different in their social behavior and innate capacities and that can be ranked as inferior or superior. Racist ideology can become manifest in many aspects of social life. Associated social actions may include nativism, xenophobia, otherness, segregation, hierarchical ranking, supremacism, and related social phenomena. Racism refers to violation of racial equality based on equal opportunities or based on equality of outcomes for different races or ethnicities, also called substantive equality.

Race is a categorization of humans based on shared physical or social qualities into groups generally viewed as distinct within a given society. The term came into common usage during the 16th century, when it was used to refer to groups of various kinds, including those characterized by close kinship relations. By the 17th century, the term began to refer to physical (phenotypical) traits, and then later to national affiliations. Modern science regards race as a social construct, an identity which is assigned based on rules made by society. While partly based on physical similarities within groups, race does not have an inherent physical or biological meaning. The concept of race is foundational to racism, the belief that humans can be divided based on the superiority of one race over another.