In human social behavior, discrimination is prejudiced treatment or consideration of, or making a distinction towards, a being based on the group, class, or category to which they are perceived to belong. These include age, caste, criminal record, height, disability, family status, gender identity, gender expression, generation, genetic characteristics, marital status, nationality, color, race and ethnicity, religion, sex and sex characteristics, sexual orientation, social class, species, as well as other categories. Discrimination consists of treatment of an individual or group, based on their actual or perceived membership in a certain group or social category, "in a way that is worse than the way people are usually treated". It involves the group's initial reaction or interaction going on to influence the individual's actual behavior towards the group leader or the group, restricting members of one group from opportunities or privileges that are available to another group, leading to the exclusion of the individual or entities based on illogical or irrational decision making.
Discriminatory traditions, policies, ideas, practices and laws exist in many countries and institutions in every part of the world, including in territories where discrimination is generally looked down upon. In some places, controversial attempts such as quotas have been used to benefit those who are believed to be current or past victims of discrimination—but they have sometimes been called reverse discrimination.