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.

That app vacuumed up information from users who gave the app permission to access their accounts ... as well as additional data from their Facebook friends,

Kogan paid about 200,000 people to take part; tens of millions of their friends were also caught in the data dragnet.

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HOW DID CAMBRIDGE ANALYTICA RESPOND?

Cambridge Analytica has denied wrongdoing, and the firm said it deleted any data it received from Kogan and denied using any Facebook data in its political work. Facebook, however, said it recently learned from journalists that Cambridge Analytica may have kept some of the data, spurring an investigation.

Kogan said he has been scapegoated by both Cambridge and Facebook. He says the data firm approached him for the project and assured him that everything he did was legal.

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WHAT'S THE CONNECTION TO THE TRUMP CAMPAIGN?