Exogamy and Endogamy
The formal rules describing those whom one should or should not marry are what anthropologists describe as rules of exogamy and endogamy.
Exogamy:
Exogamy refers to the custom of marrying to persons outside of specific community or groups. In other words, exogamy refers to the rule where a man is allowed to marry someone only outside his own group.
The system of exogamy is widely followed in India. The limits may be the family, tribe, community, the kinship group, or the race.
The most common of the exogamous rules that is followed in India says that there must not be marital relations between close blood relatives. The marriages between members of a clan are prohibited in the hindu society.
The exogamous rule is not only essential to the functioning of the family. It tends to multiply the bonds that unite the members of society together.
Endogamy
Endogamy refers to the system of rules which restricts marriages within prescribed limits. In other words, the rule of endogamy allows marriage only within a particular group or caste.
For example, the marriage in Hindus community is endogamous in the caste. It means a Hindu can marry someone within his or her own caste, though the law does not demand it.