Moiety (kinship)
In the anthropological study of kinship, a moiety () is a descent group that coexists with only one other descent group within a society. In such cases, the community usually has unilineal descent (either patri- or matrilineal) so that any individual belongs to one of the two moiety groups by birth, and all marriages take place between members of opposite moieties. It is an exogamous  clan system with only two clans.In the case of a patrilineal descent system, one can interpret a moiety system as one in which women are exchanged between the two moieties. Moiety societies operate particularly among the indigenous peoples of North America and  Australia (see Australian Aboriginal kinship for details of Aboriginal moieties).Moiety is a term used to describe two separate groups of people within one community. Two moieties may unite in certain circumstances, for example a person from one moiety can only marry a person from a different moiety.
In the anthropological study of kinship, a moiety () is a descent group that coexists with only one other descent group within a society. In such cases, the community usually has unilineal descent (either patri- or matrilineal) so that any individual belongs to one of the two moiety groups by birth, and all marriages take place between members of opposite moieties. It is an exogamous  clan system with only two clans.In the case of a patrilineal descent system, one can interpret a moiety system as one in which women are exchanged between the two moieties. Moiety societies operate particularly among the indigenous peoples of North America and  Australia (see Australian Aboriginal kinship for details of Aboriginal moieties).Moiety is a term used to describe two separate groups of people within one community. Two moieties may unite in certain circumstances, for example a person from one moiety can only marry a person from a different moiety. Moieties can also divide people for a purpose, in a positive and direct way such as separating one person’s distinct role within that community from another. Although there are many different moieties, they will always occur in pairs, for the purpose of cultural kinship systems and social organisation. A moiety is the first level within a kinship system and goes beyond people, also considering the environment as part of this moiety. Each moiety has an equal and opposite moiety, for example a man and a woman, or the land and the water. A western example of a sibling is when two children share one or both parents, however within Indigenous culture, two people may have two different parents but if their moiety is the same, they are considered siblings.

References
Further reading
"Moiety system - sociology". Encyclopedia Britannica.