In previous centuries, elections took a long time. In the 18th Century, it could take months for each constituency to hold its vote. The 1945 election took three weeks, as all the votes cast by soldiers in World War Two had to make their way back to the UK.

Now, election night is over in seconds. The exit pollAn opinion poll released on election night itself, based on responses from voters emerging from polling stations. They are generally the most accurate opinion polls. comes out when voting ends, and it is almost never wrong.

Polls have revolutionised the electoral process. But some think they are doing more harm than good.

Opinion polls have been around for a long time.

The first national poll was run in 1916 in the USA by the Literary Digest, which sent out millions of postcards to voters and simply counted the results that were sent back. Using this method, it correctly predicted every presidential election for the next 20 years.

However, in 1936 it predicted a victory for the Republican candidate Alf LandonAn American businessman and politician who was governor of Kansas from 1933 to 1937., who went on to lose in a landslide to Franklin RooseveltThe only US president ever to have served more than 2 terms. Many regard him as one of the greatest presidents in history, although he has been criticised since his own time for what have been seen as dictatorial tendencies..

George Gallup The founder of Gallup, which remains one of the world's biggest polling companies. He pioneered a new way of sampling public opinion. knew why: Literary Digest had used a self-selecting sampleA sample that is made up of people who volunteered to take to part in it. Such a sample will usually be unrepresentative of the population.. Landon had fewer supporters, but they were enthusiastic, so they were more likely to return the postcards.

Using a new method, Gallup correctly predicted Roosevelt's victory using only 50,000 respondents, compared with 2 million for Literary Digest.

Gallup had turned polling into a science. But it was not exact. In 1948, his company predicted that Republican Thomas DeweyA moderate Republican who ran for president in 1948 against incumbent Harry Truman. He was an internationalist and supporter of Roosevelt's New Deal. would beat Democrat Harry TrumanThe 33rd president of the United States and successor to Roosevelt. He remains the only world leader in history to have ordered the use of nuclear weapons.. They were humiliated when Truman trounced Dewey.

It is only recently that polls have become so central to politics. Pollsters use surveys to predict elections and find out about hot-button issues.

Public opinion can change quickly. Polls at the beginning of the 2016 EU referendum A referendum held to determine whether or not the UK should leave the EU. The Leave side won by a margin of 51.9 to 48.1. suggested Remain would win by a big margin. Leave triumphed.

Some think polls put too much pressure on politicians to do what is popular.

Journalists also get hypnotised by polls. During elections, they ask politicians about their place in the polls. Sometimes, it can seem as if the only purpose of the election is to verify the accuracy of the polling.

Others think polls are not the problem. It is useful to know what matters to people, otherwise, politicians risk losing touch. Polls are not harmful, but we are not very good at interpreting them.

Yes: Opinion polls turn politics into little more than a race. They are distractions from the real business of politics: putting forward a set of beliefs and persuading people that you are right.

No: Polls are an essential part of political life. At a time when politicians are constantly criticised for being out of touch, it would be a mistake to take away one of the few means they have of listening to voters.

Or... Polls are neither good nor bad in themselves: they are just data points. The problem is that we do not have the data literacyThe ability to interpret data and statistics accurately. to understand them properly.