When a man walked into a New York pizza parlour in December 2016 with an assault rifle and said he was checking out the story that there was a child sex-trafficking ring in the basement, run by former presidential candidate Hillary Clinton, the world took notice. It was a fake news story called "Pizzagate," planted online, that went viral. Now it's getting harder to tell truth from fiction on the Internet. But why has "fake news" spiked?  Some say it's because there's money to be made. Others say it's foreign countries trying to manipulate the outcome of important events such as the U.S. presidential election. Whatever the case, "fake news" has gone viral.

From the Curio channel: News in Review.