Cambridge Analytica harvested 87 million Facebook profiles — and Facebook let it happen

In 2018, a scandal broke that exposed how loosely Facebook had handled its users' data. A researcher named Aleksandr Kogan had built a personality-quiz app ('thisisyourdigitallife') that a few hundred thousand people took. But the app also collected data on their Facebook friends — ultimately harvesting the personal information of up to 87 million users, far more than anyone had consented to. That data was passed to the political consulting firm Cambridge Analytica.

Cambridge Analytica used the data for political profiling and targeting, including work on the 2016 US presidential election and the Brexit referendum. When the story became public, it ignited a global firestorm about privacy, consent and the power of social-media platforms. The hashtag #DeleteFacebook trended, and Facebook's reputation for handling user data was shattered.

The fallout was enormous. Facebook's founder Mark Zuckerberg was summoned to testify before the US Congress and the European Parliament. In 2019 the US Federal Trade Commission fined Facebook $5 billion — the largest privacy penalty ever — for deceiving users about their ability to control their data. Cambridge Analytica collapsed and shut down. The scandal became a defining moment in the debate over data privacy and the power of Big Tech.