Photo: A balloon chain in rainbow colours is seen in front of the Reichstag building housing the German parliament as activists of the LGBT movement demonstrate against homophobia. Photo: 17 May 2017Image copyrightDPA
The reform would give gay men and lesbians full marital rights
German MPs are expected to vote to legalise same-sex marriage, days after Chancellor Angela Merkel dropped her opposition to the idea.
The reform would give gay men and lesbians full marital rights, and allow them to adopt children.
At present, German same-sex couples are limited to civil unions.
On Monday Mrs Merkel, who previously opposed a vote on gay marriage, said she would allow MPs from her CDU party to "follow their conscience".
How did Merkel prompt the vote?
During her 2013 election campaign, Angela Merkel argued against gay marriage on the grounds of "children's welfare," and admitted that she had a "hard time" with the issue.
German Chancellor Angela Merkel. Photo: 29 June 2017Image copyrightGETTY IMAGES
Mrs Merkel says she had a "life-changing experience" when she met a lesbian couple who cared for eight foster children
But at an event hosted by the women's magazine "Brigitte" on 26 June, she shocked the German media by announcing on stage that she had noted other parties' support for it, and would allow a free vote in the future.
The usually-cautious chancellor said she had had a "life-changing experience" in her home constituency, where she had dinner with a lesbian couple who cared for eight foster children together.
As the news spread on Twitter, supporters rallied under the hashtag #EheFuerAlle (MarriageForAll) - and started calling for a vote as soon as possible.
Will the vote pass?
Yes, with strong cross-party support it is expected to.
A recent survey by the government's anti-discrimination agency found that 83% of Germans are in favour of marriage equality.
The day after the Republic of Ireland voted to legalise gay marriage in May 2015, almost every German newspaper splashed a rainbow across its front page.
"It's time, Mrs Merkel" Green party leader Katrin Goering-Eckhart exclaimed then. "The Merkel faction cannot just sit out the debate on marriage for everyone."
Why is this happening now?
Because of an upcoming general election.
Germans go to the polls on 24 September, and the sudden Merkel turnaround will deprive her opponents of a campaign issue.
The Greens, the far-left Linke, and the pro-business Free Democrats all back same-sex marriage. In fact, they have refused to enter a future coalition deal unless reform is agreed on.
Mrs Merkel's current coalition partners - the centre-left Social Democrats (SPD) - have done the same.
The right-wing Alternative for Germany (AfD) is now the only party to oppose same-sex marriage.
Conservatives within Mrs Merkel's party, the Christian Democrats (CDU), are against a change in the law, however.
They have argued that a gay marriage bill would require a change to the constitution, and that marriage between a man and a woman should enjoy special protection.
The CDU's Bavarian sister party, the Christian Social Union (CSU), has also expressed opposition.
Its members champion "traditional" families - and pragmatist Mrs Merkel needs their votes in the September election.
Commentators say this partly explains why she has rejected a vote on marriage equality until now.
How did Merkel's opponents react?
Amid a groundswell of public support for a vote, Mrs Merkel's rivals have moved to capitalise politically.
A day after her comments, the SDP's candidate for the chancellorship Martin Schulz declared - "we will take her at her word," and called for an immediate vote.
The Greens and Linke promptly backed the prospect.
The CDU responded by condemning the SDP, its coalition partner, for its "breach of trust" after four years of joint rule.
The angry exchange came just days after Mr Schulz angered conservatives by accusing Mrs Merkel of an "attack on democracy", saying she was deliberately making politics boring so that opposition supporters wouldn't bother to vote.
Has the vote been politicised?
On Wednesday, Mrs Merkel branded the political dispute "totally unnecessary" in an interview with business weekly Wirtschafts Woche (in German)..
"This isn't about some legislative footnote, but... a decision that touches on people's deepest convictions and on marriage, a cornerstone of our society", she said.
Die Welt, a German national daily agreed.
"This could have been a great moment for Germany's parliament. But the CDU/CSU have been forced into a corner and all the joy has been drained," it wrote.
Where else in Europe has same-sex marriage?
A host of European countries have beaten Germany to a same-sex marriage law.
Civil marriages are legally recognised in Norway, Sweden, Denmark (excluding the Faroe Islands), Finland, Iceland, the Netherlands, Belgium, Spain, Portugal, Luxembourg, France, the UK (except Northern Ireland and Jersey), and the Republic of Ireland.
But in Austria and Italy - as in Germany - gay couples are restricted to civil partnerships.-BBC