Facebook executives often talk about their mission as “bringing the world closer together.” With more than 2 billion users, it’s true that the platform does connect people. But one thing that Mark Zuckerberg’s two days of congressional testimony highlighted is that simply connecting people is not how Facebook reached a market cap of nearly $500 billion. At its core, Facebook is an advertising company. In 2017, 98 percent of its $40 billion in revenue came from advertising. It’s not your data that Facebook is selling, it’s your attention. Facebook’s ad platform translates your clicks and posts into “user attributes,” and places you in certain categories for advertisers. For example, your activity could suggest an that you recently had a child, that you’re a Bernie Sanders fan, or that you have an “affinity” for certain racial groups. One of the most powerful features is called “Custom Audiences,” which allows an advertiser to target individuals based on offline information such as email address or phone numbers. An advertiser can upload that data to Facebook, which will match them with its user base to find who they belong to. Then there are so-called “dark posts,” a feature Facebook is in the process of changing, which only show up in the news feeds of specific audiences and are completely hidden to everyone else. These tools can be used by anyone who wants to advertise on Facebook, and critics say that’s an open invitation for malicious actors. Watch this video to learn more about how Facebook’s ad targeting works, and why it’s so effective. Subscribe to VICE News here: http://bit.ly/Subscribe-to-VICE-News Check out VICE News for more: http://vicenews.com/ Follow VICE News here: Facebook: https://www.facebook.com/vicenews Twitter: https://twitter.com/vicenews Tumblr: http://vicenews.tumblr.com/ Instagram: http://instagram.com/vicenews More videos from the VICE network: https://www.fb.com/vicevideo