https://www.vox.com/policy-and-politics/2018/4/10/17203620/zuckerberg-testimony-questions-about-facebook-data-sharing

What does it mean for a third party to access my data? Can I do anything to stop it?

Baby pictures, vacation check-ins, your new job announcement — they all seem like innocuous posts to mark simple milestones. But your personal life is Facebook’s business. Those data points, taken together, build a powerful (and lucrative) profile of who you are and what you value.