Designed by an outside researcher named Alexander Kogan, the tool, called ThisIsYourDigitalLife, collected information not only on Facebook users who approved it but also their friends. In total, Facebook has said that Cambridge Analytica had access to data on 87 million people, including 71 million Americans, in its efforts to create detailed profiles about voters' backgrounds and behaviors, as well as what types of political messages might appeal to them based on their personalities.

Source: Los Angeles Times May 02, 2018 18:43 UTC