In order to display ads that are perfectly tailored to the user and for tracking purposes a tracking id (that identifies the device/user) is required.
A typical application for ads is frequency capping: In this case this tracking id is used to prevent the user from seeing a specific advertisement more often than desired (the ad server knows how often the advertisement has already been shown to the user).
Apple offers us two different identifiers for iOS and iPad OS.
Their advantages and disadvantages are briefly explained here.
Identifier for Advertisers (IDFA)
Apple provides the Identifier for Advertisers to track a device. The IDFA is a Universal Unique Identifier (UUID) device identifier that has the same value in all apps (no matter which vendor) on the device. This makes it possible to track the user across app boundaries.
Starting with iOS 14.5 access to the IDFA is only possible if the user grants the appropriate permission (This was introduced as part of Apple’s App Tracking transparency). To get the permission a dialog is displayed to the user:
Experience has shown that significantly less than 30% of users allow access to the IDFA.
Identifier for vendors (IDFV)
For many tracking purposes it is sufficient to have a unique ID per app and device. For this purpose Apple provides the Identifier for Vendors . The IDFV is a unique alphanumeric ID which has the same value for all of the vendor’s apps on a device. (all apps in the same vendor’s Appstore Connect account get the same IDVF value). This also enables cross-app tracking (over all apps of a vendor) on one device. The advantage of the IDFV is that no permission needs to be requested from the user. The IDFV only changes if all of a vendor’s apps have been uninstalled from the device. The IDFV cannot be used for ad attribution (“Ad Attribution connects an app install with a marketing effort”) unless the ads are internal to the vendor and only served via the vendor’s own apps (cross-promotional campaigns).
IDFA vs IDFV — Overview
Thanks for reading this little summary of IDFA and IDFV. I will update this article if there are any new developments here.
For more information on IDFA and App Tracking Transparency check my article: https://www.inovex.de/de/blog/app-tracking-transparency-and-idfa-in-ios-14-5/