Exit polls are polls taken after people exit a polling station. They differ from regular polls because they ask the electorate who they voted for at the polling station.
Exit polls usually involve a small number of the people that have already cast their votes. In each polling station, about 100 voters are interviewed regarding the candidate they voted for. The results of an exit poll are based on the group of people interviewed. Exit polls do not give an actual result but can estimate a possible outcome. Most exit polls give an accurate prediction of the results, according to The Guardian.