Gay marriage around the world
Since the Netherlands became the first country to allow same-sex marriage 12 years ago, many countries have followed suit.
France is the latest and supporters of gay marriage hope it will soon clear the final legal hurdles in Britain.
But where in the world can same-sex couples already get married?
Just after midnight on 1 April 2001, four couples - Anne-Marie Thus and Helene Faasen, and three male couples - were married by the mayor of Amsterdam, Job Cohen, in the first legal gay marriage ceremony in the world.
"We are so ordinary, if you saw us on the street you'd just walk right past us," said Ms Thus of the fuss over the televised City Hall ceremony.
"The only thing that's going to take some getting used to is calling her my spouse."
Denmark was the first country to introduce civil partnerships for same-sex couples, in 1989, but it stopped short of allowing church weddings.
Countries including Norway, Sweden and Iceland followed suit in allowing partnerships offering many - but not all - of the rights and obligations of marriage.
But it was left to the Netherlands to lead the way in allowing gay marriage, which included granting same-sex couples the right to adopt children.
It was a move welcomed by international gay rights groups as a huge step forward.Vatican intervention
A few weeks after neighbours Belgium followed the Netherlands' example in June 2003, the Vatican - in an attempt to stop further legislation - launched a global campaign against gay marriage.
In a strongly-worded 12-page document, Pope John Paul II's chief theological adviser, Cardinal Joseph Ratzinger - who would go on to become Pope Benedict XVI - warned that homosexual unions were immoral, unnatural and harmful.
Two years later, despite a 600,000-strong petition organised by a Catholic group and a rally in Madrid opposing it, same-sex marriage was introduced in Spain.
Emilio Menendez and his American partner of 30 years, Carlos Baturin German, became the first gay couple to tie the knot in Spain, at a ceremony in Tres Cantos, outside Madrid, on 11 July 2005.
Days later, Canada - where same-sex marriage had already been permitted in most provinces since 2003 - became the fourth country to introduce national legislation.
With the US reluctant to follow - a federal law still prevents US recognition of gay marriage and many states have enacted outright bans - thousands of gay Americans have visited Canada to get married since 2003.
Same-sex marriage is now allowed in nine American states as well as the District of Columbia.Court ruling
South Africa, in November 2006, became the first African country to bring in marriage for gay couples - despite homosexuality remaining taboo in large parts of the continent.
That followed a 2004 Supreme Court of Appeal ruling - brought by lesbian couple Marie Fourie and Cecilia Bonthuys - that existing marriage laws discriminated against same-sex couples.
Gay marriage timeline
- Netherlands (2001)
- Belgium (2003)
- Spain (2005)
- Canada (2005)
- South Africa (2006)
- Norway (2009)
- Sweden (2009)
- Portugal (2010)
- Iceland (2010)
- Argentina (2010)
- Denmark (2012)
- Uruguay (2013)
- New Zealand (2013)
- France (2013)
Years that same-sex marriage approved
In January 2009, Norway became the sixth country to introduce gay marriage followed, in May of the the same year, by Sweden, while a further three countries followed suit in 2010.
Divorced mothers Teresa Pires and Helena Paixao became the first gay couple to marry in Portugal, in June 2010 - a month after the law they had campaigned for came into effect - and hailed it as a "great victory, a dream come true".
The socialist government in the mainly Catholic country had faced fierce opposition from campaigners who ultimately failed to get enough support for a referendum.
Later that month, Iceland's Prime Minister Johanna Sigurdardottir married her partner, writer Jonina Leosdottir, on the day the country's gay marriage law came into force.Britain to follow?
In July 2010, meanwhile, Argentina became the first country in Latin America to legalise gay marriage.
Up until then, Mexico City had been the only place in the region where same-sex marriage was allowed. And in June 2012, Denmark became the 11th country to approve same-sex marriage - 23 years after it became the first country in the world to recognise gay civil partnerships.
More recently, both houses of Congress in Uruguay backed same-sex marriage and President Jose Mujica, who supports the bill, is expected to sign it into law.
In the UK, plans are going through the Westminster Parliament to allow same-sex marriage in England and Wales, while a bill in the Scottish Parliament is expected to receive final approval early next year. There are currently no plans for similar legislation in Northern Ireland.
In April 2013, New Zealand's parliament legalised same-sex marriage, passing the law with a large majority.
In the same month, despite deep divisions on the issue, the French National Assembly approved gay marriage legislation.
The country's conservative opposition, alongside campaigners against same-sex marriage, are taking the issue to the constitutional council, but the council is thought unlikely to block the measure.
Update 5 July 2013: This story has been changed to reflect the positions of the different nations in the UK.