Identifier For Advertisers (IDFA)

Mapendo Team
April 15, 2022
Identifier For Advertisers (IDFA)


IDFA is a unique device identifier associated with every Apple’s device and it is used in order to track users’ activities for advertising purposes. Mobile Measurement Partners (MMPs) use IDFA in order to measure the performance of app install campaigns and allow advertisers to evaluate their marketing partners.

What is IDFA?

IDFA stands for Identifier For Advertisers, and it is a unique identifier for any Apple’s device. IDFA allows MMPs to match actions like clicks on ads and impressions to installs and in-app events in order to attribute those events to the media sources which generated them. Therefore, advertisers can assess the performance of their app install campaigns and evaluate their marketing partners who are running those campaigns. 

This process is called deterministic attribution and it is 100% accurate because IDFA is unique for each device. Whenever the IDFA of the clicks matches the one of the install, the attribution is set and there is no space for mistake. 

However, in 2021 Apple  introduced iOS 14.5 which has brought big news with it. Indeed, Apple has given users the chance to hide their IDFA in order to preserve their privacy and make deterministic attribution impossible. Whenever users open a new app, they are shown a new prompt named ATT (App Tracking Transparency), which asks them whether or not they want their activity and data to be tracked across apps. By opting-out this prompt users can hide their IDFA, choosing not to receive targeted and personalized ads. 

Why is it important?

IDFA has been the core of mobile attribution because of its 100% accuracy. MMPs could track users’ IDFA in order to carry out deterministic attribution and provide advertisers and marketers with indisputable data about app install campaign performance. 

Indeed, deterministic attribution allows advertisers to evaluate their marketing partners and to compute their Return On Ad Spend. At the same time, it helps marketers to better analyze app install campaigns and to optimize them in real time. 

Apple’s release of iOS 14.5 has significantly affected deterministic attribution because most users have since decided to hide their IDFA and not to be tracked across apps. However, Apple has given advertisers, MMPs and marketers an alternative, which is SKAdNetwork, their own attribution technology. 

SKAdNetwork allows deterministic attribution when users hide their IDFA. It sends cleaned data about installs to advertisers and marketers with a delay of 24-48 hours, in order to make it impossible to track those users’ data. In addition, it does not track post-install events at a granular level, but measures them with a 6-bit system, which makes it difficult to optimize in real time app install campaigns towards in-app events. 

What you need to know about IDFA?

  • IDFA is an identifier which is unique for any Apple’s device;
  • IDFA is used to track users for advertising and marketing purposes;
  • IDFA allows MMPs to carry out deterministic attribution in order to measure app install campaigns;
  • With iOS 14.5, Apple has given users the opportunity to hide their IDFA and not to receive personalized ads;
  • When users choose to hide their IDFA, deterministic attribution is possible only through SKAdNetwork, Apple’s attribution technology.