How did a Facebook personality quiz become a tool for political targeting? In this episode of Facts Tell, we revisit the Cambridge Analytica scandal to examine how personal data can be collected and used to shape the messages people receive online. According to a US Federal Trade Commission complaint, an app used by around 270,000 people also harvested data from tens of millions of their Facebook friends. The data helped build personality profiles intended for voter targeting. We explore how such practices, alongside personalized feeds and repeated messaging, can reinforce existing beliefs and narrow exposure to different perspectives.