A Same-sex union refers to an enduring relationship between two people of the same gender.

Literary, historical, and archaeological evidence of such unions has been found for a number of diverse cultures as early as 2400 B.C. in ancient Egypt, ancient Greece, ancient China, ancient Japan, and among the traditions of North American native cultures.

Currently, same-sex union refers to a legally recognized union, regulated by national law or by the laws of a sub-national jurisdiction, such as a state, province, county, or city. Denmark was the first country to offer legal recognition nationwide, beginning in 1989. The Netherlands was the first to offer full same-sex marriage, in 2001. Some religious bodies also recognize same-sex unions.

The terms used to designate legally recognized same-sex unions are not standardized, and vary widely from country to country. The exact level of rights and benefits also varies, depending on the laws of a particular country.

See the following articles for further discussion of these terms:

• same-sex marriage - marriage between two people who are of the same sex.
• civil union - generally speaking, a status equivalent or identical to marriage for same-sex couples. In some jurisdictions, such as Portugal, Quebec and New Zealand, civil unions are also open to opposite-sex couples.
• civil partnership - a civil union for same-sex couples in the United Kingdom, which is practically identical to marriage in all but name.
• registered partnership -- a term for civil unions in several European countries, such as the Scandinavian countries and Switzerland.
• life partnership - a term for civil unions in Germany.
• civil pact of solidarity - a term for civil unions in France, also open to opposite-sex couples.
• stable union of couples - a term for civil unions in Andorra.
• significant relationship - a term for civil unions in Tasmania, an Australian state. "Caring relationships" are available for relatives, as well.
• domestic partnership - a term for same-sex unions most often used by states, provinces, or municipalities in North America, with lesser status and fewer benefits than a civil union. Domestic partnerships may also be open to opposite-sex couples.
• reciprocal beneficiaries - a term for domestic partnerships in Hawaii, an American state, also open to relatives.

Some jurisdictions may recognize equivalent same-sex unions created in other jurisdictions, but again, laws vary widely from one country or state to another. In the United States, the 1996 Defense of Marriage Act bars the federal government from recognizing any same-sex unions, and does not require any state to recognize such unions created by another state.

• blessing of same-sex unions - the religious recognition of a same-sex couple, currently offered by several Christian and Jewish religious bodies in a number of developed countries around the world.

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