Same-sex marriage, that is also known as gay marriage, is the marriage of two people of the same sex or gender. As of 2022, it was known that marriage between same-sex couples is legally performed and recognized in 30 countries (nationwide or in some jurisdictions) with the most recent being Chile in March 2022 and Switzerland starting 1 July 2022. Adoption rights are not necessarily covered, though most states with same-sex marriage allow those couples to jointly adopt. In contrast, 34 countries (as of 2021) have definitions of marriage in their constitutions that prevent marriage between couples of the same sex, most enacted in recent decades as a preventative measure. Some other countries have constitutionally mandated Islamic law, which is generally interpreted as prohibiting marriage between same-sex couples. In six of the former and most of the latter, homosexuality itself is criminalized. There are records of marriage between men dating back to the first century. In the modern era, marriage equality for same-sex couples was first legally acknowledged in the Netherlands on 1 April 2001 The application of marriage law equally to same-sex and opposite-sex couples (called marriage equality) has varied by jurisdiction and has come about through legislative change to marriage law, court rulings based on constitutional guarantees of equality, recognition that marriage of same-sex couples is allowed by existing marriage law, and by direct popular vote (via referendums and initiatives). The most prominent supporters of same-sex marriage are human rights and civil rights organizations as well as the medical and scientific communities, while the most prominent opponents are religious fundamentalist groups. Polls consistently show continually rising support for the recognition of same-sex marriage in all developed democracies and in some developing democracies.     Scientific studies show that the financial, psychological, and physical well-being of gay people is enhanced by marriage and that the children of same-sex parents benefit from being raised by married same-sex couples within a marital union that is recognized by law and supported by societal institutions. Social science research indicates that the exclusion of same-sex couples from marriage stigmatizes and invites public discrimination against gay and lesbian people, with research also repudiating the notion that either civilization or viable social orders depend upon restricting marriage to heterosexuals. Same-sex marriage can provide those in committed same-sex relationships with relevant government services and make financial demands on them comparable to that required of those in opposite-sex marriages, and also gives them legal protections such as inheritance and hospital visitation rights. Opposition to same-sex marriage is based on claims such as that homosexuality is unnatural and abnormal, that children are better off when raised by opposite-sex couples, that same-sex couples cannot procreate, and that the recognition of same-sex unions will promote homosexuality in society. The former two claims are refuted by scientific studies, which show that homosexuality is a natural and normal variation in human sexuality, and that sexual orientation is not a choice. Many studies have shown that children of same-sex couples fare just as well as the children of opposite-sex couples; some studies have shown benefits to being raised by same-sex couples. Terminology Alternative terms Some proponents of the legal recognition of same-sex marriage—such as Marriage Equality USA (founded in 1998), Freedom to Marry (founded in 2003), and Canadians for Equal Marriage—have long used the terms marriage equality and equal marriage to signal that their goal was for same-sex marriage to be recognized on equal ground with opposite-sex marriage. The Associated Press recommends the use of same-sex marriage over gay marriage. Use of the term marriage Anthropologists have struggled to determine a definition of marriage that absorbs commonalities of the social construct across cultures around the world. Many proposed definitions have been criticized for failing to recognize the existence of same-sex marriage in some cultures, including in more than 30 African cultures, such as the Kikuyu and Nuer. With several countries revising their marriage laws to recognize same-sex couples in the 21st century, all major English dictionaries have revised their definition of the word marriage to either drop gender specifications or supplement them with secondary definitions to include gender-neutral language or explicit recognition of same-sex unions. The Oxford English Dictionary has recognized same-sex marriage since 2000.     Opponents of same-sex marriage who want marriage to be restricted to pairings of a man and a woman, such as The Church of Jesus Christ of Latter-day Saints, the Catholic Church, and the Southern Baptist Convention, use the term traditional marriage to mean opposite-sex marriage. History Ancient A reference to marriage between same-sex couples appears in the Sifra, which was written in the 3rd century CE. The Book of Leviticus prohibited homosexual relations, and the Hebrews were warned not to “follow the acts of the land of Egypt or the acts of the land of Canaan” (Lev. 18:22, 20:13). The Sifra clarifies what these ambiguous “acts” were and that they included a marriage between same-sex couples: “A man would marry a man and a woman a woman, a man would marry a woman and her daughter, and a woman would be married to two men.” What is arguably the first historical mention of the performance of marriages between same-sex couples occurred during the early Roman Empire according to controversial historian John Boswell. These were usually reported in a critical or satirical manner.     Child emperor Elagabalus referred to his chariot driver, a blond slave from Caria named Hierocles, as his husband. He also married an athlete named Zoticus in a lavish public ceremony in Rome amidst the rejoicings of the citizens. According to Craig A. Williams some Romans as early as the first century clearly did participate in formal ceremonies in which two males were married. These marriages were seen as atypical: Williams writes that “a marriage between two fully gendered ‘men’ was inconceivable; if two males were joined together, one of them had to be ‘the woman.’” The first Roman emperor to have married a man was Nero, who is reported to have married two other males on different occasions. The first was with one of Nero’s own freedmen, Pythagoras, with whom Nero took the role of the bride. Later, as a groom, Nero married Sporus, a young boy, to replace his wife Poppaea Sabina following her death, and married him in a very public ceremony with all the solemnities of matrimony, after which Sporus was forced to pretend to be the female concubine that Nero had killed and act as though they were really married.A friend gave the “bride” away as required by law. The marriage was celebrated in both Greece and