For example, if you Like Game of Thrones on Facebook, expect to be served an HBO ad for the show in a partner app. While it’s extremely targeted to an individual, Facebook is not sharing personal information with third parties. Instead, it’s using the unique identifier on a mobile device.
Here’s what happens when you load an app that’s using Audience Network to serve ads. When you sign into Facebook on a mobile device, that device shares the device’s unique identifier number (on an iOS device it’s called the IDFA while on Android it’s called the unique ID) That number is then associated with your Facebook account.
When you launch an app that is part of the Audience Network on that same device, it pings Facebook with the device’s identifier number. Facebook sees that number and serves an ad to the app based on relevant information you’ve shared with Facebook. The ad appears in the app and personal information is never shared with the third-party.
Advertisers get to extend the reach of their ads. Meanwhile users will get ads that are relevant to their interests.