LONDON (Reuters) - The United Kingdom votes on Thursday. Here is a guide to how the election will work.
Polls open at 7 a.m. (0600 GMT) and close at 10 p.m. (2100 GMT), though anyone who is in the queue to vote when the polls close may do so. Voting is not compulsory.
Britain is a parliamentary democracy, meaning that the government is formed from lawmakers rather than being separately elected.
The defining principle for any prospective government is that it has the support of a majority of lawmakers in the elected lower chamber of parliament, the House of Commons.
The national election is thus the election for the House of Commons. Voters are asked to elect a member of parliament for their local constituency, which on average have about 72,000 voters.
Britain's first-past-the-post electoral system means a winner-takes all situation. There is no system of proportional representation for candidates who come second in each constituency.
For the election to produce a majority government, the biggest party theoretically must win at least 326 seats of the 650 regional constituencies. But in practice, the threshold for a majority is around 323, because the Irish republican Sinn Fein party does not take up any seats it wins in Northern Ireland.
A party which wins a majority will seek to implement policy proposals which it set out during the campaign. By convention, the unelected upper house, called the House of Lords, will not block or hinder policies that were pledged during the campaign.
If the government has a small majority or needs to enter coalition, its ability to run the country will be typically tested by a vote on the Queen's Speech -- a speech at the start of a parliament setting out a legislative agenda which has been prepared by the prospective government and is read out by Queen Elizabeth.
Turnout at national elections in Britain has fallen since the 1950s, when it used to be over 80 percent.
The number of register voters in the 2015 general election was 46.4 million. Turnout was 66.4 percent, the highest turnout since 1997.
Turnout was higher at the 2016 referendum on EU membership, with 72.2 percent of an electorate of 46,500,001 voting.
The deadline to register to vote was Monday May 22. On one day alone, the electoral commission received 622,000 applications.
The greatest spike in applications to register was among young people, with nearly 250,000 applications from under 25s on the day of the deadline. In 2015, turnout among those aged 18-24 was just 43 percent.
The opposition Labour Party polls better with younger voters, while May's Conservatives are more popular with older generations.
In all, more than one million people under 25 have registered to voted since the election was announced in April, compared to around 700,000 in the same time period ahead of the 2015 election. Fewer over 55s have registered this time around compared to two years ago.
However, the Electoral Commission said that approximately 30 percent of under 34s had not been registered compared to 4 percent of over 55s.
Estimates from 2015 suggest that approximately 85 percent of the eligible population are registered to vote.
Parliament was officially dissolved on May 2 and all 650 seats declared vacant.
Prime Minister Theresa May and her team of ministers remain in charge of their departments and retain their ministerial decision-making power.
But, by convention, the government refrains from taking major policy decisions, entering new long-term commitments or making high-profile appointments.
If a national emergency forces the government to act quickly, it may consult with the opposition informally to discuss the best course of action. When a new parliament is formed, it may be required to endorse actions taken during the interim period.
Theresa May's Conservatives currently hold a working majority of 17, and she called the early election in the hope of increasing it. The polls indicate she will win, though it is unclear by how much.
There is a large discrepancy between the pollsters, even as the consensus is that May wins while Labour has closed the gap on the Conservatives.
Polling firms widely predicted there would be no overall majority in 2015, with Labour possibly the largest party. The Conservative victory - and majority - came as a shock to pollsters and has prompted soul-searching.
"From the pollsters' point of view this is an experimental election," YouGov's Anthony Wells said in a blog post. "We all got it wrong in 2015 and we are all trying different methods to get it right this year."
Wells said that polls in 2015 over-estimated how likely young voters were to vote, and the difference between the pollsters this time around stems from the varied approaches to the problem that the firms are taking this time around
Queen Elizabeth has the power to dismiss a prime minister or to make a personal choice of successor but a monarch has not exercised this right since 1834 and the tradition is considered archaic.
By long-standing convention the queen does not get involved in party politics, and the formation of the next government is left to the parties to resolve amongst themselves.
Reporting by William James and Alistair Smout; Editing by Guy Faulconbridge