Discrimination is the prejudicial treatment of an individual based on their membership in a certain group or category. It involves the actual behaviors towards groups such as excluding or restricting members of one group from opportunities that are available to another group. The term began to be used as an expression of derogatory racial prejudice in the 1830s from Thomas D. Rice's performances as "Jim Crow".
Since the American Civil War the term 'discrimination' generally evolved in American English usage as an understanding of prejudicial treatment of an individual based solely on their race, later generalized as membership in a certain socially undesirable group or social category.
Discriminatory laws such as redlining exist in many countries. In some places, controversial attempts such as racial quotas have been used to redress negative effects of discrimination.
It should be noted that discrimination is not always against a disadvantaged group. When a majority group (white, male, heterosexual, rich etc.) is discriminated against because they are a member of this group this is usually called reverse discrimination.