Starting today (4/9/18), Mark Zuckerberg's company will send messages to the 87 million users who had their data improperly given to the firm.
Cambridge Analytica was connected to Donald Trump's presidential campaign and used the data to target people during the election.
All of the more than 2 billion Facebook users will get notices about protecting their information.
Have you been notified? What concerns do you have about your data being shared with Cambridge Analytica?