Once the polls close on Thursday at 10pm, all eyes will be on the exit poll to predict the eventual result.
Exit polls have been used to predict the results of general elections for years and years – with varying degrees of accuracy.
In 2010, the exit poll correctly predicted a hung parliament, with the same happening in 2017 when it said no party would receive a majority in the snap election in June.
How many seats would a party need for a majority?
A party needs at least 326 seats out of the 650. All 650 seats are up for the vote in a general election.
If no single party achieves a majority, larger parties can collaborate with smaller parties which agree to support them and form a coalition government.
What is predicted at the moment?
YouGov’s constituency-by-constituency poll predicts the Conservatives are on course for a 28 seat majority – but the margin of error and unknown impact of tactical voting means a hung parliament is still a possibility.
The pollsters, who have analysed more than 100,000 voter interviews over the past week, predicted the Tories will win 339 seats and Labour 231.
A 28-seat majority would be the best Tory result since Margaret Thatcher’s showing in 1987 – but it is down from the sizeable 68-seat victory that the same YouGov-style poll had been predicting only two weeks ago.
Which are the marginal seats we should watch?
Here are the most marginal seats being contested in this election, together with the majority of the winning party in 2017.
Fife North East (won by the SNP in 2017): 2
Kensington (Lab): 20
Perth & Perthshire North (SNP): 21
Dudley North (Lab): 22
Newcastle-under-Lyme (Lab): 30
Southampton Itchen (Con): 31
Richmond Park (Con): 45
Crewe & Nantwich (Lab): 48
Glasgow South West (SNP): 60
Glasgow East (SNP): 75