In mobile apps, there are no cookies. Instead, Ad Manager uses user-resettable identifiers provided by the mobile device’s operating system. Typical advertising IDs are AdID (Android) and IDFA (Apple). Mobile advertising IDs allow developers and marketers to track activity for advertising purposes. They’re also used to enhance serving and targeting capabilities.
Mobile advertising ID benefits
These advertising IDs allow buyers to match their data about users to the user behind an impression received from an exchange. This promotes effective remarketing, frequency capping, and conversion tracking on Ad Exchange inventory. In addition, it enables advertisers to more effectively measure the performance of their campaigns through improved tracking and attribution, which will unlock new monetization opportunities for publishers.
To better inform your audience about how advertising IDs from their device will be used, we require that publishers using mobile advertising IDs comply with the disclosure requirements in the "In-App Ad Remarketing" provisions of the Google Ad Manager Partner Guidelines.