Jon Swartz, and Marco della Cava

USA TODAY

SAN FRANCISCO — Fake content is a genuine problem on the Internet.

Between fake news that sways elections, fake apps that trick shoppers and fake book reviews that stymie sales, the web has seen a surge in fantastic, misleading and outright false messaging that threatens to make the truth hard to find.

No doubt humans have been exaggerating for millennia. But our 21st-century bonfire of digital falsehoods is fueled by a unique set of circumstances that blends our innate interest in the outrageous with the explosion of a social-media echo chamber. Not surprisingly, this has created an opportunity for shadowy entrepreneurs to exploit both for profit.

If you've yet to run across this faux phenomenon, your introduction likely isn't far off. The problem is mushrooming fast.

One researcher recently tallied a list of nearly 60 fake online news sites, ranked based on whether they peddled outright fabrications or sly satire. Services such as Google and Facebook have recently vowed to crack down on fake news. Analytics firm Jumpshot looked at more than 20 known fake news sites and determined that Facebook referrals accounted for half of their traffic, resulting in millions of likes.

Fake apps present Google and Apple with a Whack-A-Mole problem, where as soon as an offending app is removed, others pop up in its place.

Hackers use typosquatting to dupe the unwary with fake news, sites

And Amazon recently removed several reviews of a new book by Fox News personality Megyn Kelly. At one point, more than half were one-star thrashings, according to Slate, and the book's publisher said it was an effort to discredit the journalist and Trump foe.

It's not The Onion

In truth, the venom in a spiteful book review likely gives away the bias of its author. And 99 cents lost on an app that promised to give your phone X-ray powers won't ruin your day.

But fake news arguably packs the power to dilute the importance of a free press, supplanting traditional fact-based journalism with shareable and often unsourced news snacks that reinforce a specific point of view. For instance, a story that Pope Francis had endorsed Donald Trump for president was shared hundreds of thousands of times before it was debunked.

"I'm a fan of The Onion, but it’s been made extremely clear it is satire. It is one thing to lampoon news, it is another to fabricate it. This, increasingly, is driving our lives," says Jessica Pucci, Ethics & Excellence Professor of Practice, Walter Cronkite School of Journalism & Mass Communication at Arizona State University.

The right's turn to censor?: Glenn Reynolds

Jeanne Bourgault, CEO of Internews, a non-profit that ensures access to reliable news in 90 countries, says she's spent decades fighting the spread of propaganda and hate speech in places like the Soviet Union, South Sudan and Kenya.

“It’s starting to feel like situations in other countries,” she says, adding that U.S. citizens can be trained to spot fake news, but are better served by subscribing to trusted, reputable local media.

That's a tall order in an era where anger and divisiveness often ruled the recent presidential campaign, say psychologists.

Ryan Martin, an anger researcher and chairperson of the psychology department at the University of Wisconsin-Green Bay, says studies show anger is the most viral emotion online — and often is what drives people to share content.

"If you truly hate someone or something, it reinforces a negative attitude," Martin says. "It also rationalizes things, such as a belief in voter fraud and the birther movement. Articles play into our already congruent narrative about candidates."

And most of those articles are shared via social network circles. Today, popular platforms such as Twitter and Facebook allow faux information to rocket worldwide at the click of a mouse or touch of a screen. Social sites represent the go-to news source for 62% of adults, up from 49% in 2012, according to a Pew Research Center survey.

False CNN-porn report shows how fast fake news spreads

What's more, the very nature of social media platforms prioritizes news that boasts the most engagement, which when shared repeatedly, creates a virus-like effect that spreads the disinformation far and wide before it's called out as fake.

"All content is made to please," says ASU's Pucci. "We want to elicit reaction from our audience. A story is now good not just if it’s well reported and written, but if it reaches people. Facebook does that. It allows people to target (both) accurate and fake news to audiences."

The very real pitfalls of our fake-nation include the suggestion that fake news on Facebook may have played a role swaying the election, as exemplified by fake news reports trumpeting that Hillary Clinton had been arrested by federal agents before Election Day.

The solutions range from having social media platforms better patrol their sites to simply getting used to taking everything online with a healthy dose of skepticism.

Often, the perpetrators of these deceptions aren't bored teens but organized enterprises that cash on the traffic generated by sites that often resemble the originals, including an outfit out of Tbilisi, Georgia, that created a fake USA TODAY website with the URL www.usatodaycom.com.

Fake news threatens democracy, Obama says

Facebook and Google have heard the hue and cry.

Google announced that it would ban fake news websites from using its online ad service, while Facebook CEO Mark Zuckerberg promised in a recent blog post to develop better ways for users to identify fake content — while reiterating that he doesn't feel his platform should be "arbiters of truth."

This current appetite for fake news may have cultural roots. Our social media- and gossip-obsessed culture “softened us up for fiction, with little time for introspection,” says Keith Ablow, a psychiatrist and author of Living the Truth: Transform Your Life Through the Power of Insight and Honesty​.

“We’re particularly vulnerable now to fake news because many of us are faking our lives via technology,” he says. “When we construct our lives on Facebook or texts or gaming, many of us are creating false narratives through fabulous exotic vacation photos, celebrity selfies and fantasy games. Our thirst for authenticity is waning. News is one aspect of that.”

Fake news warning label was not from Facebook

That wasn't the case five to six years ago, he says, when the food chain of news consumption was different.

Then, a patently false account had to work its way from blog posting to social media to mainstream media to spill into the mainstream. Now, with Facebook hovering at 1.8 billion members and Twitter the communication mode of choice for president-elect Trump and his 16.4 million followers, social media is the blowtorch from which stories emerge, metastasize and instantly become gospel to millions.

A recent tweet by president-elect Trump alleging that Hillary Clinton had won the popular vote due to irregularities — "In addition to winning the Electoral College in a landslide, I won the popular vote if you deduct the millions of people who voted illegally" — raced around the news-o-sphere before being condemned by Trump's close advisor, Newt Gingrich.

Fake app whack-a-mole

Fake apps for Apple and Android operating systems are increasingly becoming breeding grounds for fraudsters who see an opening to peddle bogus products and collect sensitive personal information.

Chris Mason, co-founder of Branding Brand, a Pittsburgh-based app developer, started noticing “hundreds” of phony apps on those virtual stores in September as the holiday push neared.

“Mobile shopping has finally really taken off this year,” Mason says. “And only one out of three retailers has an app, so there was a void.”

He alerted Google and Apple and many were taken down, but not all of them. There are still “dozens” that look like the real thing, Mason says, pointing to phony apps for retailers such as Dillard’s, Foot Locker, Nordstrom and Pandora Jewelry.

Mason suggests downloading the app from the retailer’s website — not the app store — to ensure it’s authentic and check reviews. If they are from upset customers, odds are it's fake, he says.

Google said in a statement it takes security "seriously," scans for "potentially malicious apps" and relies on its network of developers and users to "flag apps" for additional review.

More fake news on the Web — this time, via Google

"We strive to offer customers the best experience possible and we take their security very seriously," Apple said in a statement. "We’ve set up ways for customers and developers to flag fraudulent or suspicious apps, which we promptly investigate to ensure the App Store is safe and secure. Users have to allow permissions for apps, which they can easily disable."

To millennials, this new rash of fake news might seem alarming. But the fact is that fabricated news accounts, lascivious gossip and sensationalized tabloids have been popular and influential in the U.S. for decades, says Steve Miller, a journalism professor at Rutgers University.

Grand precedent: HG Wells

There's a grand tradition of fabricated news in America media, Miller and others point out, dating to the murky origin of the Spanish-American War in 1898, and the roles William Randolph Hearst, owner of the New York Journal, and Joseph Pulitzer of the New York World played in stoking conflict to help them sell papers at the dawn of the yellow journalism era.

"Fake news has always been popular, whether it be The National Enquirer, Weekly World News, Globe," Miller says. "And innovation has made it possible to spread that news faster and deeper." A radio broadcast of War of the Worlds, Orson Welles' Halloween Eve hoax in 1938 about a Martian invasion on Earth, created a nationwide panic. It was also a hit.

Clifford Irving's made-up autobiography of reclusive billionaire Howard Hughes was an international best-seller in 1971, and tabloid rags like Weekly World News survive to this day, dishing up tantalizing headlines such as "Bat Child Found In Cave!" and "Elvis Is Alive — And Running For President!"

And if there's one truism in fake news: It's nothing without Elvis.

Contributing: Jefferson Graham in Los Angeles and Elizabeth Weise in San Francisco.

Follow USA TODAY San Francisco Bureau Chief Jon Swartz @jswartz and tech reporter Marco della Cava @marcodellacava