Scotland's First Minister Nicola Sturgeon has confirmed she will set in motion the formal move towards another independence referendum.
More than two years after the first referendum decided Scotland would stay part of the UK, she said the Brexit vote and proposed terms of negotiation mean the Scottish public should decide the matter once again.
But how does she propose it will it happen and what might Westminster do?
Here are all the key questions answered on the road to IndyRef2:
When does the first minister want the vote to take place?
Ms Sturgeon said the poll should be held between autumn 2018 and spring 2019, notably while Brexit negotiations are likely to still be ongoing.
Downing Street condemned the call for the repeat vote and its proposed scheduling, saying: "Another referendum would be divisive and cause huge economic uncertainty at the worst possible time."
How can Ms Sturgeon justify a vote after the 2014 referendum result?
Scotland's vote in September 2014 to remain part of the UK, by a rough majority of 55% to 45%, is pointed to by some as a decisive line in the sand.
But the SNP's large gains in membership and the near-complete sweep of Scottish Westminster seats in the 2015 general election greatly emboldened the referendum's defeated side.
In 2016 the party won a third term in power at Holyrood - though lost the overall majority - with a campaign manifesto to push for a second referendum if either of the following two conditions were met:
- If there is clear and sustained evidence that independence has become the preferred option of a majority of the Scottish people.
- If there is a significant and material change in the circumstances that prevailed in 2014, such as Scotland being taken out of the EU against our will.
While current polling suggests the SNP's first condition has not been met, the UK's overall vote to leave the EU last year, despite 62% of Scots voting to remain, satisfies the second condition, giving Ms Sturgeon grounds for the repeat push for a vote to offer a permanent divorce from the rest of the UK.
So why has the SNP moved now and not after the Brexit vote?
The SNP clearly believes it has the grounds to demand a repeat on the basis the action is against its will, claiming its suggested "compromise" measures - chiefly the UK or Scotland alone remaining in the single market - has been ignored by the UK government.
What steps need to be taken?
Ms Sturgeon announced she will ask the Scottish Parliament next week for permission to request a Section 30 order from Westminster, the necessary legal power required for a referendum ballot.
She can expect the Scottish Parliament to support her, as the six pro-independence Scottish Green Party MSPs should help the minority-SNP carry a majority at Holyrood.
The Scottish Government has already carried out a consultation on a draft Referendum Bill, which sets out how a second vote on independence could be held.
What is the UK government and Westminster likely to do in response?
Prime Minister Theresa May has not yet said if the Conservatives would seek to prevent a referendum from being held by voting against the section 30 order. Instead, the Tories say simply that a second referendum should not be held.
However, a number of senior politicians at Westminster, including Labour leader Jeremy Corbyn, have said that Westminster should not seek to block a fresh vote on independence despite his and others' overall opposition to the campaign for independence.
If Westminster does not oppose Holyrood, how would the timing be decided?
It is not entirely clear but it is most likely to need another agreement between the Scottish and UK governments, in a similar way to the Edinburgh Agreement, which outlined how the 2014 referendum would be held.
Despite Ms Sturgeon's push for vote in the autumn of 2018, Downing Street may attempt to delay another vote until after Britain has exited the EU.
That is timetabled for two years after Article 50 is triggered, as planned, at the end of this month but even that date is still far from certain given the anticipated lengthy negotiations.