How did things get to this point?

When the Scottish National Party won a landslide victory in Scotland in May 2011, the political pressure for a vote became irresistible. In 2012, British Prime Minister David Cameron agreed to hold a straight "yes" or "no" referendum, excluding a third option of giving the Scots more autonomy (which he is now offering anyway).

Who's in favour?

The pro-independence campaign is led by Alex Salmond, whose Scottish National Party won an unexpected majority in the Scottish Parliament in 2011. He is promising Scots that they can keep everything they like about the union – the Queen, the pound, the BBC and free healthcare – and get rid of everything they do not like; like austerity and the Conservative Party of David Cameron. The campaign has some support from celebrities including Sir Sean Connery, Gerard Butler and Frankie Boyle.

Who's opposed?

The anti-independence camp, which calls itself Better Together, is a coalition of British political parties. It politely advocates a vote of "no thanks", appealing to a shared sense of history and Britishness. It is spending much of its time telling Scots that if they vote for independence, they can never share the pound – or go back. The no campaign has enjoyed the most high-profile support, including Sir David Attenborough, Dame Judi Dench, Susan Boyle, Jo Brand and Sir Mick Jagger.

What happens if the vote succeeds?

If Scotland votes to separate, it will take 18 months of negotiations before independence is declared. And judging from the tone of the campaign, it will be a messy and acrimonious divorce. Scotland already administers many of its own affairs. After a referendum in 1997, it set up its own parliament and controls health, education, housing, justice and a portion of taxation. But some economists say an independent Scotland would be too poor to keep up its welfare state, let alone expand it.

Who can vote?

The referendum will be open to voters as young as 16, even though the national voting age is 18. Only residents of Scotland can vote. But that has not deterred expatriate Scots or really anybody else from joining the fray.

Which side is winning?

Until recently, the anti-independence campaign maintained a comfortable lead in opinion polls. But as the referendum approaches, the two sides are neck and neck.

Will the Queen have to go?

Mr Salmond thinks Queen of the Scots is a "fantastic title" and has promised fellow Scots that they get to keep Elizabeth II as their head of state, Australian-style. The Queen herself has urged voters, somewhat cryptically, to "think very carefully about the future".

What would the United Kingdom be called without Scotland as a member?

The British government has awkwardly named it the "continuing United Kingdom". The Scottish government prefers to call it the "rest of the United Kingdom", or UK.