Untouchability is a form of social institution that legitimises and enforces practices that are discriminatory, humiliating, exclusionary and exploitative against people belonging to certain social groups. Untouchability also refers to the condition of belonging to such groups, members of whom are historically called untouchables, outcastes, or archaically pariahs. Although comparable forms of discrimination are found all over the world, untouchability involving the caste system is largely unique to South Asia.