Korean clans

Korean clans are groups of people that share the same paternal ancestor. They are indicated by the combination of a bongwan and a family name. For example, the Jeonju Yi clan is identified by the city Jeonju and family name Yi, the Gimhae Kim clan is identified by the city Gimhae and family name Kim, and the Aphae Jeong clan is identified by the island Aphae-do and family name Jeong.

Korean clans are used to distinguish clans that happen to share the same family name The bongwan system identifies descent groups by geographic place of origin. However, a clan name is not treated as a part of a Korean person's name. The bongwan and the family name are passed on from a father to his children, thus ensuring that person in the same paternal lineage sharing the same combination of the bongwan and the family name. A bongwan does not change by marriage or adoption.

Bongwan are used to distinguish different lineages that bear the same family name. For example, the Gyeongju Kim and the Gimhae Kim are considered different clans, even though they happen to share the same family name Kim. In this case, Gyeongju and Gimhae are the respective bongwan of these clans.

Different family names sharing the same bongwan sometimes trace their origin to a common paternal ancestor, e.g. the Gimhae Kim clan and the Gimhae Heo clan share Suro of Geumgwan Gaya as their common paternal ancestor, though such cases are exceptional.

According to the population and housing census of 2000 conducted by the South Korean government, there are a total of 286 surnames and 4,179 clans.

Restrictions on marriage and adoption
Traditionally, a man and a woman in the same clan could not marry, so the combination of the bongwan and the family name of a husband had to differ from that of a wife. Until 1997, this was also the law, but this was ruled as unconstitutional.

When adopting a child, the adoptive father and the adopted child must share the same combination of the bongwan and the family name. However, in exceptional circumstances, adoptive parents can change an adopted child’s family name for the adopted child's welfare. In this case, the adoptive parents must visit a family court to request permission to change the family name.