We have all heard the term exit poll before, but what are they, how do they work and can they be trusted?

Exit polls are indications of how people voted, based on interviews with voters as they leave polling stations.

Tomorrow, the BBC, ITV and Sky will team up to produce an exit poll for the 2019 general election.

Tens of thousands of interviews will be conducted at 144 polling stations across the country.

As they leave the polling stations, voters will be given a mock ballot paper to complete, just as they did inside.

A group of analysts and experts will then use the collected date to produce a statistical model to predict the results nationwide.

It will be fourth exit poll produced in partnership by the three broadcasters and will be announced at 10pm, after the polls close.

Professor Sir John Curtice, political commentator for BBC News, said: "The principal aim of the exit poll is to help viewers and listeners to navigate the initial hours of election night as the first results come in.

"By comparing the actual results with the forecast of the exit poll, we will be able to point to the political direction in which Britain is now apparently headed."

In 2017, the exit poll predicted a hung parliament, despite Theresa May's Tories being ahead in the opinion polls throughout the campaign.

By the end of the night the exit poll’s predicted result was confirmed, with the Tories taking 317 seats - only three more than the exit poll predicted - and Labour taking 262, four fewer than estimated.

There have been mishaps with exit polls in the past, however.

In 2015, the exit poll indicated that a hung parliament was on the cards, with the Tories as the largest party.

Yet David Cameron ended up producing the first outright Tory majority in more than 20 years.

Plymouth University's Professor Colin Rallings, elections analyst for ITV News, said: "A volatile electorate, views on Brexit which cut across traditional party lines, and an election in the depths of winter all pose particular challenges for this year's exit poll.

"But as ever, our experienced team will be working to ensure that another politician has to 'eat their hat' for doubting the story the poll foretells at ten o'clock on December 12."

Sky News election guru Professor Michael Thrasher added: "In pubs and clubs, in homes around the country, people are watching and waiting for the 'exit poll moment', as the broadcasters time the declaration for the stroke of ten o'clock.

"Shock, disbelief, denial and disappointment for some. A pleasant surprise for others as the forecast exceeds expectations."