Fake news is a term that’s become popular today, but what does it actually mean? And how pervasive is it?

What is fake news?

There is a lot of questionable content on the internet these days: offensive speech; hyperpartisan points of view around political issues; and even information that people may have thought was true — but later turned out to be incorrect. None of these, though, are examples of fake news.

Rather, fake news is fiction masquerading as fact. It is written by authors who know it is fiction, but hope to convince readers that it is fact, in the interest of having it read and circulated. And it is often designed to appear as if it is from a traditional news source. The original goal behind fake news was economic: to generate advertising revenue for the site hosting the content. Thus, fake news is quite distinct from hyperpartisan or biased news, both of which may present content from one particular — and sometimes even extreme — viewpoint, but are indeed believed to be correct by the people writing the stories. Fake news, on the other hand, is known to be false by the authors of the pieces themselves.

Who shares fake news?

In a recent article published in Science Advances, we documented that surprisingly few people, less than 10 percent, shared links to a list of the most notorious fake news sites on Facebook during the 2016 election in the United States. And while our research showed that older people were significantly more likely to share fake news than younger people, fake news was shared by people of all age groups — though those aged 18 to 29 were by far the least frequent offenders.

How to identify fake news

There are some simple things to consider. What is the source of a news story? Does it come from an established source that is known to follow high journalistic standards? Many online sites use domain names that are subtle modifications of well-known sites to try to fool readers. Does the news story contain quotes from named individuals? Typical journalists will include such quotes. And finally, there are fact-checking sites that are readily available such as snopes.com or factcheck.org where one can check the veracity of stories.

Crucially, reporters in the mainstream media aim to write stories that are correct. To do so, they adhere to journalistic standards, often obtaining multiple sources for what they print. These reporters do make mistakes sometimes. But when they do, they generally admit it. Sometimes, but quite rarely, there are even reporters who commit fraud — but these people are fired when they are caught. To put it simply, the norm in these publications is that they are trying to report the truth. That presentation of truth might appear biased to the eyes of some beholders, or to be one perspective on events — but it is not fake.

The economic and political motives behind fake news

Probably the best-known fake news website was the Denver Guardian. It was a website that was run by someone who openly admits to writing “political fanfiction,” and whose stated goal was to make money. This was the same goal of the producers of fake news from Macedonia, who set up websites designed to look like legitimate news sites in the United States. These people were not Russian-backed operatives trying to influence a U.S. election; they were independent entrepreneurs trying to make money by taking advantage of the demand in the United States for extreme stories about U.S. political figures.

We can expect that more fake news — especially around elections — will be crafted for political, as opposed to economic, reasons. This is dangerous, because, as with the fake news crafted for economic reasons, it has the potential to lead to a less well-informed electorate. Voters already tend to be relatively uninformed about politics; throwing incorrect — and often intentionally deceptive — information into the mix can only make things worse.

But perhaps even more important, the mere existence of fake news can decrease trust in real news if people do not know the difference between media following traditional journalistic norms and websites that are in the business of producing “political fanfiction” rather than news.

If fake news leads to more people believing falsehoods about politics, it will not be good for democracy. If fake news leads to people no longer trusting any media to deliver facts about politics, it will be a disaster for democracy.

What can be done?

Of course we need to educate people on how to spot fake news. But we also need to be very careful about how we discuss fake news. Fake news is not news with which you disagree. It is not news produced by legitimate news organizations that may eventually be found to have contained errors. And it is not opinions in newspapers and online that are an affront to your values.

Fake news is fiction masquerading as fact, produced by organizations that do not follow any journalistic practice, let alone best practices. Calling news sources that share information with which you disagree “fake news” — a disturbing habit of our president — may ultimately be more dangerous than fake news itself.

Jonathan Nagler is a professor of politics and codirector of the Social Media and Political Participation (SMaPP) lab at New York University. Joshua A. Tucker is a professor of politics, director of the Jordan Center for the Advanced Study of Russia, and codirector of the Social Media and Political Participation (SMaPP) lab at New York University. Andy Guess is an assistant professor of politics and public affairs at Princeton University.