What is the identifier for advertisers (IDFA)?

The identifier for advertisers (IDFA) is a random device identifier assigned by Apple to a user’s iOS device. Advertisers can use this device ID to track data so they can deliver customized advertising. The IDFA is used for tracking and identifying a user (without revealing personal information) and linking user actions and events to campaigns and channels.

The data can then be used to attribute users to specific sources and gain a clear picture of how the types of users that different sources provide, thereby enabling precise campaign optimization and a data-driven user acquisition strategy.

The IDFA can also identify when users interact with a mobile advertising campaign, provided the channel offers IDFA tracking and the advertiser tracks users who interact with ads successfully. If this occurs, the IDFA can identify whether specific users click an advert.

IDFAs are important because they are an accurate means to track iOS users. By assigning a device to a single IDFA, advertisers have crystal clear certainty about the defining qualities of that user and are able to accurately attribute them to the correct advertising campaign.

The IDFA can be reset at any time by the user on each iOS device by going to security and privacy, selecting tracking, and toggling ‘Allow Apps to Request to Track’ off and then on (if they wish to have it on). Each time it is toggled off and on again, the IDFA is reset. While the IDFA’s depersonalization of user data offers a certain level of data protection, it still ultimately allows advertisers and marketers to leverage device specific data and perform targeted advertising as a result. More on this below.

The Android equivalent to the identifier for advertisers is the Google Advertising ID (GAID), sometimes referred to as the Android Advertising ID (AAID). Users can also access and reset their GAID to opt-out of personalization in their Android privacy settings.

The ability for advertisers to access the IDFA was drastically reduced with the rollout of iOS 14.5 in April 2021 and its corresponding App Tracking Transparency (ATT) framework. Once a device is running iOS 14.5 or later, advertisers and marketers are required to request permission to access the IDFA and track the user at this device ID level. If the user does not opt-in to allow tracking via the IDFA, the only way to perform attribution for campaigns run on iOS is via Apple’s SKAdNetwork (SKAN).

Along with the mobile marketing industry, Adjust is already on the path toward an attribution framework that leverages machine learning and predictive analytics to enable campaign optimization from aggregated data sources. While device-level data will always be useful, and can play a large role in informing the next-generation solutions, future-proof marketing strategies will deemphasize it in favor of privacy-centric, predictive campaign optimization models.

For ATT opted-in users, however, the IDFA is recognized by Adjust as a valid form of identification for conducting attribution. We don’t track any device IDs by default, nor do we store them—we only use them for attribution purposes.

The image below demonstrates the flow under which the IDFA is collected, according to the user settings and choices. If ‘Allow apps to request to track’ is toggled on in the user’s privacy settings, a prompt can be served. If consent is granted via that prompt, the IDFA is collected. If consent is denied or the setting is turned off by default, the IDFA will not be available.