iOS
IDFA
The IDFA (Identifier for Advertisers) is a unique ID issued by Apple for each device. The IDFA remains unchanged even if the app is reinstalled. If the user opts out of tracking, the IDFA is collected as00000000-0000-0000-0000-000000000000. The same applies to iOS simulators.
The following cases are considered as the user opting out of tracking.
- The user didn’t respond to the ATT prompt or was not prompted.
- The user didn’t allow tracking on the ATT prompt.
- The user falls into a certain age group, and ad tracking is not allowed based on age restrictions.
- The user turned on “Allow Apps to Request to Track” to automatically deny app tracking requests.
- The user allowed tracking on the ATT prompt, but opted out of tracking in the device settings.
About Limit Ad TrackingLimit Ad Tracking has been deprecated since iOS v.14.0.
- iOS v.14.0 to v.14.1: Ad tracking is always restricted.
- iOS v.14.2 to v.14.4: Ad tracking is restricted if the “Allow Apps to Request to Track” option is turned on.
- iOS v.14.5 and later: Ad tracking is always restricted.
IDFV
The IDFV (Identifier for Vendors) is a unique ID issued by the iOS app vendor. All apps from the same vendor on a device will have the same IDFV. If the user deletes all apps from the same vendor from the device and reinstalls an app from the same vendor, the IDFV will reset.How the device ID for iOS is determined
By default, the IDFA is used as the device ID. The IDFV is used if the user did not allow tracking on the ATT prompt or if the app runs on the iOS simulator. If no IDFA or IDFV is available, a randomly generated ID is used as the device ID.Android
GAID
The GAID (Google Advertising Identifier) is a unique ID issued by Google Play for each device. The GAID remains unchanged even if the app is reinstalled. The GAID is only reset when the user manually resets it from the device settings. Note that GAID is not collected on devices such as Amazon FireStick where Google Play is unavailable. If the user limits ad tracking on the device, GAID is collected as00000000-0000-0000-0000-000000000000.