The Inian caste system describes the social stratification and social restrictions in the Indian subcontinent, in which social classes are defined by thousands of endogamous hereditary groups, often termed as jātis or castes. Within a jāti, there exist exogamous groups known as gotras, the lineage or clan of a person, although in a handful of sub-castes like Shakadvipi, endogamy within a gotra is permitted and alternative mechanisms of restricting endogamy are used (e.g. banning endogamy within a surname).