NEW YORK (AP) — Facebook is facing the most serious crisis in its 14-year history as it deals with fallout from a major leak of user data to political consultants associated with the 2016 Trump campaign.

Here's a look at the scandal and what it means.

WHAT'S GOING ON?

The U.K.-based data-mining firm Cambridge Analytica has been accused of lifting the Facebook profiles of more than 50 million users without their permission in order to manipulate elections. A former employee of the firm, Christopher Wylie, played a role in that action, and later told his story to journalists.

The crisis has renewed questions about Facebook's ability to protect the privacy of its users while also exploiting their personal details to fuel its lucrative advertising business. It has also deepened concerns about the social media network's ability to avoid being exploited to spread propaganda and sway elections.

Authorities in both the U.S. and the U.K. are investigating both Facebook and Cambridge Analytica. Facebook shares have fallen and some users are contemplating deleting their accounts.

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WHAT DID CAMBRIDGE ANALYTICA DO?

Wylie says the firm sought Facebook information in order to build psychological profiles on a large portion of the U.S. electorate. He said the company was able to amass the database quickly with the help of an academic, Aleksander Kogan, who developed a Facebook app called "This is Your Digital Life" that appeared to be a personality test.