Thanks to the Guardian and the NYT inquiries, released in March 2018, now we know the story of the biggest scandal of 21st Century.
Cambridge Analytica was a communicaton company whose strenght was the collection of people online data and their analysis in order to manipulate people ideas. Moreover Cambridge Analytica, for its business, was used to create bot account (autonomous program on a network which can interact with systems or users) and modulated them according to the progress of public opinion, to address it in the way they wanted. For those particular skills and thanks to its founders (Mercer and Bannon), Cambridge Anaytica had been hired for the 2016 US Presidential Election, working for Trump campaign. For this occasion Cambridge Analytica, with hidden agreements, and against Facebook policy, took all the millions of data collected by the app thisisyourdigitallife and used them to target and manipulate US electors, with a special algorythm created (maybe unawares) by a Cambridge University researcher, Michal Kosinski.