Former British Prime Minister Gordon Brown speaks at a rally against Scottish independence Wednesday, September 17, in Glasgow, Scotland. Scots <a href="index.php?page=&url=http%3A%2F%2Fwww.cnn.com%2F2014%2F09%2F09%2Fworld%2Feurope%2Fscottish-referendum-explainer%2Findex.html">will head to the polls</a> on Thursday, September 18, to vote on a referendum that could end Scotland's 307-year union with England and Wales as Great Britain -- and launch it into the world as an independent nation.
Scotland divided over independence —
Former British Prime Minister Gordon Brown speaks at a rally against Scottish independence Wednesday, September 17, in Glasgow, Scotland. Scots will head to the polls on Thursday, September 18, to vote on a referendum that could end Scotland's 307-year union with England and Wales as Great Britain -- and launch it into the world as an independent nation.
LEON NEAL/AFP/Getty Images
People gather during a pro-independence rally in Glasgow on September 17.
Scotland divided over independence —
People gather during a pro-independence rally in Glasgow on September 17.
David Cheskin/AP
A bakery in Edinburgh, Scotland, reveals the results of a tasty straw poll it has held since March 7. It has been selling cupcakes with the Scottish flag (yes to independence), the British flag (no to independence) and a question mark (undecided).
Scotland divided over independence —
A bakery in Edinburgh, Scotland, reveals the results of a tasty straw poll it has held since March 7. It has been selling cupcakes with the Scottish flag (yes to independence), the British flag (no to independence) and a question mark (undecided).
Matt Cardy/Getty Images
People hold "no" banners during a pro-union rally in Edinburgh on Tuesday, September 16.
Scotland divided over independence —
People hold "no" banners during a pro-union rally in Edinburgh on Tuesday, September 16.
Matt Dunham/AP
A spray-painted "yes" for independence is seen on the cliffs in Eyemouth, which is on Scotland's North Sea coast, on September 16.
Scotland divided over independence —
A spray-painted "yes" for independence is seen on the cliffs in Eyemouth, which is on Scotland's North Sea coast, on September 16.
Scott Heppell/AP
A pro-independence campaigner canvasses voters in Edinburgh on September 16.
Scotland divided over independence —
A pro-independence campaigner canvasses voters in Edinburgh on September 16.
Matt Dunham/AP
Darren Brander shows his support for Scottish independence outside his home in Glasgow on Monday, September 15.
Scotland divided over independence —
Darren Brander shows his support for Scottish independence outside his home in Glasgow on Monday, September 15.
Danny Lawson/PA/AP
A man hangs a banner on a "Better Together" campaign office in Glasgow on September 15.
Scotland divided over independence —
A man hangs a banner on a "Better Together" campaign office in Glasgow on September 15.
Danny Lawson/PA/AP
Independence supporters take a selfie ahead of a concert in Edinburgh on Sunday, September 14.
Scotland divided over independence —
Independence supporters take a selfie ahead of a concert in Edinburgh on Sunday, September 14.
LEON NEAL/AFP/Getty Images
Pro-union supporters gather during a rally in Edinburgh on September 14.
Scotland divided over independence —
Pro-union supporters gather during a rally in Edinburgh on September 14.
BEN STANSALL/AFP/Getty Images
An independence supporter takes part in a march to the BBC Scotland offices in Glasgow on September 14.
Scotland divided over independence —
An independence supporter takes part in a march to the BBC Scotland offices in Glasgow on September 14.
Jeff J. Mitchell/Getty Images
A dog wears a "no thanks" badge during a pro-union rally in Edinburgh on September 14.
Scotland divided over independence —
A dog wears a "no thanks" badge during a pro-union rally in Edinburgh on September 14.
BEN STANSALL/AFP/Getty Images
Members of the "Generation Yes" youth organization campaign in Glasgow on Saturday, September 13.
Scotland divided over independence —
Members of the "Generation Yes" youth organization campaign in Glasgow on Saturday, September 13.
Matt Cardy/Getty Images
A member of the Grand Orange Lodge of Scotland prepares for a march in Edinburgh on September 13. The Orange Order is a conservative British unionist organization.
Scotland divided over independence —
A member of the Grand Orange Lodge of Scotland prepares for a march in Edinburgh on September 13. The Orange Order is a conservative British unionist organization.
BEN STANSALL/AFP/Getty Images
People campaigning for both sides of the independence referendum clash in Glasgow on Friday, September 12.
Scotland divided over independence —
People campaigning for both sides of the independence referendum clash in Glasgow on Friday, September 12.
Robert Perry/Rex
An independence supporter rides a decorated bicycle during a rally in Glasgow on September 12.
Scotland divided over independence —
An independence supporter rides a decorated bicycle during a rally in Glasgow on September 12.
Andy Buchanan/AFP/Getty Images
People in Edinburgh, Scotland, hold leaflets September 12 campaigning against independence.
Scotland divided over independence —
People in Edinburgh, Scotland, hold leaflets September 12 campaigning against independence.
Matt Cardy/Getty Images
Scotland's First Minister Alex Salmond arrives to speak at a news conference in Edinburgh on September 12. Salmond has been a vocal proponent of independence.
Scotland divided over independence —
Scotland's First Minister Alex Salmond arrives to speak at a news conference in Edinburgh on September 12. Salmond has been a vocal proponent of independence.
Matt Cardy/Getty Images
First-time voters who are 16 years old depart BBC's Big, Big Debate in Glasgow on Thursday, September 11. Thousands of young voters from all over Scotland attended the debate, where they got a chance to quiz a panel of politicians on the referendum.
Scotland divided over independence —
First-time voters who are 16 years old depart BBC's Big, Big Debate in Glasgow on Thursday, September 11. Thousands of young voters from all over Scotland attended the debate, where they got a chance to quiz a panel of politicians on the referendum.
Jeff J. Mitchell/Getty Images
British Deputy Prime Minister Nick Clegg speaks to members of the media in Selkirk, Scotland, on Wednesday, September 10. He and British Prime Minister David Cameron were in Scotland to make the case for voting "no" to independence.
Scotland divided over independence —
British Deputy Prime Minister Nick Clegg speaks to members of the media in Selkirk, Scotland, on Wednesday, September 10. He and British Prime Minister David Cameron were in Scotland to make the case for voting "no" to independence.
Ian Forsyth/Getty Images
"No" is written on a "yes" campaign placard in Selkirk on September 10.
Scotland divided over independence —
"No" is written on a "yes" campaign placard in Selkirk on September 10.
Ian Forsyth/Getty Images
British Labour Party politician Alistair Darling campaigns for a ''no'' vote in Glasgow on September 10.
Scotland divided over independence —
British Labour Party politician Alistair Darling campaigns for a ''no'' vote in Glasgow on September 10.
Mark Runnacles/Getty Images
A woman looks from a window next to a "yes" campaign sign in Edinburgh on Tuesday, September 9.
Scotland divided over independence —
A woman looks from a window next to a "yes" campaign sign in Edinburgh on Tuesday, September 9.
Jeff J. Mitchell/Getty Images
A man attends a pro-union "Better Together" rally in Edinburgh on Monday, September 8.
Scotland divided over independence —
A man attends a pro-union "Better Together" rally in Edinburgh on Monday, September 8.
Andy Buchanan/AFP/Getty Images
Members of the "English Scots for Yes" campaign hold a tea party Sunday, September 7, in Berwick-upon-Tweed, England, which is near the Scottish border.
Scotland divided over independence —
Members of the "English Scots for Yes" campaign hold a tea party Sunday, September 7, in Berwick-upon-Tweed, England, which is near the Scottish border.
Jeff J. Mitchell/Getty Images
The national flag of the United Kingdom, left, and the national flag of Scotland fly above buildings on Downing Street in London.
Scotland divided over independence —
The national flag of the United Kingdom, left, and the national flag of Scotland fly above buildings on Downing Street in London.
Simon Dawson/Bloomberg/Getty Images