CNN
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What are exit polls? It is a series of surveys that ask voters who they voted for, as well as additional questions about their political views, the factors they considered in the election and their own background more broadly.

That helps us better understand who turned out to vote, how different groups of people voted and what they think about some of the campaign’s biggest issues.

The first results from this year’s exit polls will be reported after 5:00 PM ET on Election Day. Data that could characterize the outcome of a race is not reported until after the polls close.

Exit polls are conducted by Edison Research for the National Election Pool on behalf of a consortium of media companies: CNN, ABC, CBS and NBC. They get their name because on Election Day, interviewers are stationed outside about 500 polling places across the country, where they conduct surveys of a randomly selected sample of voters who have just cast their ballots. The voting locations were self-selected through random sampling, meaning the resulting interviews had to be representative of Election Day voters statewide or nationally. The interviewers call back several times a day to report their results – meaning the initial numbers will likely change as more data comes in.

But the exit poll doesn’t start on Election Day: it also tries to represent the views of the millions of Americans who cast their ballots before November 5. Interviewers are also being placed at approximately 100 early in-person voting locations in some states.

And the results also include voters who voted early absentee or voted by mail. This part of the electorate is reached through more traditional election surveys, which are conducted by calling, emailing and sending text messages to people chosen from lists of all registered voters.

In addition to the national exit polls, exit polls are also conducted in specific states with important, competitive presidential or down-ballot races. This year, those states include Arizona, Georgia, Florida, Michigan, Nevada, North Carolina, Ohio, Pennsylvania, Texas and Wisconsin.

Personal exit polls are conducted using paper surveys that respondents complete themselves; those reached by email or text answer the questions online, while those reached by phone answer questions asked by a live interviewer. Each exit poll contains approximately 20 to 25 questions and lasts approximately five minutes. Each voter’s answers are anonymous.

Ultimately, exit polls will include interviews with tens of thousands of voters. That scope makes them a powerful tool for understanding the demographic profile and political views of voters in this year’s elections. And their findings will ultimately be weighed against the ultimate benchmark: the results of the election itself.

Yet exit polls are still polls, with a margin for error, meaning they are most useful when treated as estimates, not precise measurements. This applies in particular to the first exit poll figures, which have not yet been adjusted to the final election results.

CNN’s Jennifer Agiesta contributed to this report.