1. A firm tied to the Trump campaign used private information — including contacts and “likes” — harvested from the Facebook profiles of more than 50 million users without their permission.

The Times teamed up with The Observer of London for the investigation into Cambridge Analytica, a voter-profiling company bankrolled by conservative investors that worked on the 2016 Trump campaign. Above, Christopher Wylie, who helped found the company and worked there until 2014.

Facebook banned the firm after we started asking about its practices; the firm, which paid an outside researcher for the data, is facing scrutiny from investigators and lawmakers on both sides of the Atlantic.