This is the best tl;dr I could make, original reduced by 90%. (I’m a bot)
Former White House senior strategist Steve Bannon and billionaire Robert Mercer sought Cambridge Analytica’s political ad targeting technology as part of an “Arsenal of weapons to fight a culture war”, according to whistleblower Christopher Wylie.
Cambridge Analytica improperly obtained the personal information of millions of Facebook users to build profiles of US voters in order to target them with personalised political advertisements, via a related UK-based entity called SCL Elections.
A year later the Guardian published an article revealing that Cambridge Analytica was using the Facebook data to target voters for Ted Cruz’s presidential campaign.