Millions of are visiting polling stations today to choose who their next MP and, by extension, the next government will be.
From 7am to 10pm on Thursday, polling stations across the country will be open for to put an X in the box next to the name of the person they want to represent them in the House of Commons.
But, polling day will result in the one survey which has become increasingly accurate in recent years: the exit poll.
Here's everything you need to know it.
Arguably the most-pressing question, and the one with the simplest answer.
The exit poll will come out soon after 10pm.
Pollsters from Ipsos Mori visit 144 polling stations across the UK and ask tens of thousands of to privately fill in a replica ballot paper as they leave. This gives an indication of how they've voted.
Replica ballot papers and boxes are used to “maximise the confidentiality of ’s votes”, according to polling expert Sir John Curtice.
Workers from the polling company tend to go to the same locations at each general election as these have been chosen to be demographically representative of the country, with rural and urban seats, and weighted slightly in favour of marginal areas.
Sir John explained: “Wherever possible we go back to the same places as last time. The method of the exit poll is that you compare the results in the selected polling stations this time, with the results of the exit poll last time.”
With regards the reason for using a ballot paper and box, he added: "To ask them to tell an interviewer, then they might be reluctant to do that, so you’re trying to minimise the level of refusal, which is always an issue.”
The number of approached at a polling station is known as a “systematic sample”, Sir John said, and the size of the samples varies according to the registered electorate for that area.
They've got better as the years have gone on.
The first one in 1974 predicted a 132-seat majority for Labour. In reality, it was three.
Sir John, professor of at Strathclyde University in Glasgow, said: “It’s tended to be relatively accurate, it’s not perfectly accurate, but there’s been a number of occasions in which it has ended up proving rather more accurate than what the opinion polls have been.
