Newt Gingrich has won the latest contest to become the Republican candidate in this year's US presidential election.
AP Photo, Matt Rourke
Voters in the state of South Carolina handed him a convincing victory over all his party rivals, in a result that was until just a couple of days ago considered highly unlikely.
Gingrich, a former speaker of the House of Representatives, had previously performed poorly in his attempt to land the Republican nomination, coming fourth in the contest in Iowa and fifth in New Hampshire.
His success in South Carolina, in particular the size of his win over the former frontrunner Mitt Romney, has suddenly made the identity of the eventual Republican presidential candidate far harder to predict.
Here's a guide to what has just happened and why it's significant.
What is the South Carolina primary?
An election organised by the state's local government to allow citizens to indicate who they would like to see become the Republican candidate in this year's presidential election. Anybody of voting age (18 or over) can take part, including people registered as Democrats.
What was the result?
What does the result mean?
Based on the percentage of votes received, each candidate will be awarded a number of delegates to represent them at the Republican party's national convention in August, where the person to challenge Barack Obama in the presidential election will be formally chosen.
How many delegates has Gingrich won in South Carolina?
Nearly all of them: at least 23 of the 25 that were up for grabs. But these are the first delegates Gingrich has won in the whole race to date. Mitt Romney has picked up 33, thanks mostly to his win in New Hampshire, while Rick Santorum has 14, due to his strong performance in Iowa.
How many delegates are needed to become the official presidential candidate?
A total of 1,144. Only 62 were at stake in Iowa, New Hampshire and South Carolina.
So there's a long way still to go?
Was Gingrich expected to win this particular contest?
Not at all. In mid-January, Romney had an opinion poll lead over all other candidates of around 10%. Gingrich ended up winning the primary by 12%: a change of 22% in one week.
This is something of a shock result?
Why did he do so well?
He has benefited from the withdrawal from the race of Rick Perry, who went on to endorse Gingrich, and from a narrowing in the field of anti-Romney candidates. Romney was perceived to have struggled to put in a convincing performance in the latest live TV candidates' debates. This seems to have been the cue for a majority of Republican voters, who polling suggests have never liked Romney, to give their support to Gingrich, whose feisty contribution to the TV debates clearly struck a chord.
Who won the South Carolina primary during the last presidential election?
John McCain, who went on to be the Republican presidential candidate.
Is history on Newt Gingrich's side?
Precedent suggests so. Ever since the first South Carolina Republican primary in 1980, the winner in this state has always gone on to be the official Republican candidate in the presidential election.
But haven't there been three different winners in each of the three contests so far?
Indeed. Santorum has now been declared the official winner in Iowa, despite the result initially implying Romney was the victor. Romney won in New Hampshire. Never before have the first three contests in the Republican nomination battle been won by three different people.
How might Obama be feeling about all of this?
The president's re-election team will be enjoying seeing their opponents fighting among themselves and giving victory to the likes of Gingrich, a man on the right of the Republican party who prides in entertaining some rather extreme views. But they will also be frustrated at not knowing who exactly they ought to be planning to beat in the election on 6 November.
What happens now?
The next Republican contest takes place in Florida on 31 January.
And who is expected to win there?
Mitt Romney is the favourite, and is currently enjoying double-digit leads in the opinion polls. But Romney had been considered the favourite in South Carolina, where he had also been registering the same sort of support. Given the events of the last 48 hours, the outcome in Florida is now probably too close to call. Gingrich does not have quite as much money or resources as his main rival. But there are two live TV debates in the state between now and 31 January. Gingrich will be hoping to use them to improve his chances in much the same way as he did, to evident success, during the debates in South Carolina.