Carole Cadwalladr

Donald Trump's victory was engineered by ultra-conservative billionaire Robert Mercer. Buying Breitbart News, he inserted Steve Bannon into the campaign. Another Mercer company, Cambridge Analytica, micro-targeted the American voters most likely to swing for Trump. In the final days of the campaign, they deployed "dark posts", manipulative Facebook ads seen only by the user before disappearing.

Explore how a data company named Cambridge Analytica came to symbolize the dark side of social media in the wake of the 2016 U.S. presidential election.