It's variously being called one of the biggest data leaks in Facebook history and "unequivocally not a data breach." And it has lawmakers on both sides of the Atlantic clamoring for answers. This weekend thrust Cambridge Analytica into the spotlight: In 2014, some 270,000 Facebook users took the quiz developed by researcher Aleksandr Kogan for Cambridge Analytica, purportedly for academic purposes. It provided a gateway into their friends' data, improperly giving Cambridge Analytica, which has been tied to President Trump's 2016 campaign, data on some 50 million Facebook users. Among the thorniest accusations: that it allegedly kept the information after saying it deleted it, and that Facebook has known about the incident for at least two years. The latest developments and reaction: