Voting closes at the nearly 400 local counting areas across the country
7:30 p.m. (ET)/12:30 a.m. (BST)
Early results are expected to start rolling in. Sunderland, a Labour Party stronghold located in the northeast of England, is expected to be among the first to declare results
8:15 p.m. (ET)/1:15 a.m. (BST)
Vote results from Northern Ireland are expected to filter in
9 p.m. (ET)/2 a.m.(BST)
Many of the Scottish areas are expected to start reporting
10 p.m. (ET)/ 3 a.m. (BST)
More than half of all areas are expected to report between 10 and 11:30 p.m. (ET)/3 to 4:30 a.m. (BST)
1 a.m. (ET)/ 6 a.m. (BST)
Areas expected to report around this time are also anticipated to be among some of the strongest results for the Leave campaign.
2 a.m. (ET)/ 7 a.m. (BST)
The last declaration is expected around 7 a.m. The final result will be announced in Manchester by Jenny Watson, Chief Counting Officer.
On June 23 people in the United Kingdom will be asked to vote on a simple question:
Should the United Kingdom remain a member of the European Union or leave the European Union?
What do the polls say?
For weeks, Remain held a slight lead, then Leave pulled ahead last week and now the race is about evenly split, based on a comprehensive poll of polls.
52
Support Remain
48
Support Leave
In photos: Britons off to the polls for historic vote Britons turned out to cast their ballots at a variety of polling stations from swimming pools, laundromats, boxing clubs and hair salons on Thursday, June 23, 2016. The outcome of the close race between the Remain and Leave sides will decide the country's future in the European Union.
Why now?
To quell growing dissention within the Tory party and the rise in popularity of the Euro skeptic United Kingdom Independence Party, UKIP, Prime Minister David Cameron promised in 2013 to hold a referendum on the EU if his party won the election in 2015.
Then-prime minister Pierre Trudeau urged the UK to stay in the European Economic Community during the referendum in 1975. GLOBE AND MAIL ARCHIVES
Britain has been a member of the EU, and its predecessor, since 1973. Two years later, however, Britain held a similar referendum, asking citizens if the country should stay in what was then called the European Economic Community. Sixty-seven per cent of Britons voted yes.
That evolved into the EU in 1993. British governments, particularly those led by Tories, have balked at what they see as the transformation of the EU into a political union and the country has opted out of several EU programs including the euro.
What is the EU?
The EU has 28 member states that sends members to the European parliament and abide by the European Court of Justice among other institutions. It has its own currency, the euro, used by 19 members; a parliament; central bank; court of justice; a flag.
Many members of the EU also belong to the euro zone and/or the Schengen Area.
The euro zone is a group of 19 EU states that use the euro and fall under the European Central Bank.
The Schengen Area is named after the town in Luxembourg, where the agreement was signed in 1985. It provides the passport-free movement of people.
Of the EU states, 26 belong to Schengen in one way or another. Three other non-EU countries, Iceland, Norway and Switzerland, are associated members. Britain and Ireland do not belong.
If Britain leaves the EU, the Comprehensive Economic and Trade Agreement, known as CETA, could be in trouble. That agreement has already been seven years in the works and has yet to be ratified by the EU or its member states. Brexit would probably distract the EU for years and put CETA on hold even longer.
A Brexit would likely also cause big headaches for Canadian companies. Canadian firms choose to do business in Britain because it's a "beachhead" to launch into the EU but still shares a language and similar laws with Canada.
One thing is clear: The debate about Britain's potential departure also recalls when Quebeckers voted twice in referendums in which hard economics yielded to emotion and nearly broke up Canada, The Globe and Mail's Jeffrey Simpson writes.
A “Britain Stronger in Europe” campaigner hands out leaflets and stickers to pedestrians in London, U.K., on Monday, June 6, 2016. U.K. Prime Minister David Cameron said he’ll hold a long-pledged referendum on the U.K.’s membership of the European Union on June 23.
Mr. Cameron, 23 senior cabinet ministers, the Labour Party, the Liberal Democrats, most economists, the Organization for Economic Co-operation and Development, the International Monetary Fund, most of Britain’s allies, including Canada and the United States, most large employers, most trade unions, 13 Nobel laureates.
Some notable supporters of `Remain`:
David Cameron, UK Prime Minister
Christine Lagarde, Managing Director of the IMF
Barack Obama, U.S. President
Angela Merkel, German stateswoman and chancellor
Why?
The Remain side believes that it would be an economic disaster for Britain to pull out.
Roughly 40 per cent of British trade is with the EU and the London financial district has become a world leader because of its unfettered access to the EU. Leaving would mean slower economic growth, job losses, higher prices and potentially a recession.
The Remain side says Britain should reform the EU from within and says Britain's influence globally would be reduced outside the EU.
A campaigner arranges "#Lexit The Left Leave Campaign" leaflets on a table in Manchester, U.K., on Saturday, June 11, 2016.
Matthew Lloyd/Bloomberg
Who wants to leave?
Seven senior cabinet ministers, including Boris Johnson, who is seen as a future prime minister, roughly half of the Conservative caucus, several large businesses, UKIP, the Sun newspaper.
Some notable supporters of `Leave`:
Boris Johnson, former Mayor of London
Nigel Farage, UK Independence Party leader
Marine Le Pen, head of France's far-right Front National party
Donald Trump, U.S. presidential candidate
Why?
The Leave side says unrestricted immigration from the EU, particularly Eastern Europeans, has hurt the housing market and employment.
It says that leaving the EU would give Britain control over its borders and free the country from mountains of EU red tape. Cutting payments to the EU would also save the British government billions of dollars and allow for more spending on health care and other priorities.
Britain could negotiate its own trade deals with the EU and other countries, much like Canada does.
Economics tend to trump other issues in voters' minds, but the problem for Remain is that many voters, 45 per cent, do not believe that leaving the EU would make them personally worse off. That's a sign that the Remain side's message is not getting through. Leave's problem is that voting patterns in other referendums, including in Canada, show that there is a late surge in support for the status quo. That happened in the Scottish referendum in 2014. Despite polls showing majority support for independence, 55 per cent of voters opted to stay in the United Kingdom.
What's the reaction globally?
Financial markets in Europe have swung wildly lately as support for Leave has increased. Investors have also been snapping up 10-year German and British bonds, or gilts, a sure sign that many are looking for a safe harbour. Yields on German bonds went negative for the first time recently and British gilts touched record lows. The pound has also been on a roller coaster and some say its value could fall by as much as 20 per cent if Brits vote to leave.
How does it breakdown within the UK?
Polls show that Scotland, Northern Ireland and Gibraltar are overwhelmingly in favour of Remain. Londoners also support Remain, but by a lower margin. The rest of England and Wales are divided. Experts say that for the Leave side to win, it must win England, including London, by at least four percentage points.
If Leave wins and Scots voted overwhelmingly for Remain, Scottish First Minister Nicola Sturgeon, who heads the Scottish National Party, has suggested that the country could hold another referendum on independence.
Read Mark MacKinnon's take on the anti-immigrant fear and angry nationalism baring its teeth across the UK.
Polling shows a deep divide in the country along socio-economic lines. As one polling expert put it, this is a struggle between the winners of globalization and those who feel left behind. There is also a growing backlash against elites. And there is trouble for Mr. Cameron, as cabinet ministers trade insults and a growing number of MPs call for him to resign regardless of the result.
Under Article 50 of the EU treaty, a member choosing to leave has two years to negotiate a new arrangement with the EU (the deadline can be extended with unanimous consent). Any new deal would have to be ratified by each EU member. During that period, Britain would remain a full EU member.
CORRECTION: An earlier version of this story stated that Britain joined the EU through a referendum vote in 1975. Britain actually joined the European Economic Community in 1973. The referendum held in 1975 was to see if Britain should stay a part of EEC.
Leave or Remain: How markets will react to Brexit vote Global financial markets have become captivated by the whims of British public opinion. The Globe's Tim Shufelt weights in on how various asset classes might react to the vote.
As Brexit vote looms, investors brace for falloutNow keenly aware of the threat of Britain exiting the European Union, investors this week will be fixated on the potential for Thursday’s referendum to wreak havoc on markets.
Margaret Wente: Those deranged BrexitersAhead of the vote, there’s only one certainty: Many Britons are tired of hearing the elites lecture them about their own self-interest
Boris Johnson, former Mayor of London
Nigel Farage, UK Independence Party leader
Marine Le Pen, head of France's far-right Front National party
Donald Trump, U.S. presidential candidate
