Overview

The Identifier for Advertising (IDFA) is a unique identifier assigned to a device by Apple for tracking advertisements.

What is Identifier for advertising?

The Identifier for Advertising (IDFA) is a random number generated by Apple and assigned to a device, such as an iPhone, iPad, or iPod Touch. It allows advertisers and app developers to track user data in a manner that maintains the privacy and security of the user. Apple first introduced IDFA in iOS 6, replacing its predecessor, the Unique Device Identifier (UDID). Unlike the UDID, which was commonly linked with privacy issues, the user controls the IDFA, enabling them to switch it off or change it at their discretion.

Formula

Example

Why is IDFA important?

For ecommerce businesses, the IDFA is crucial as it facilitates target advertising. Advertisers use this information to understand and serve personalized ads based on user interests. Furthermore, it enables tracking of user interactions with these ads and the effectiveness of the advertising campaigns.

Which factors impact IDFA?

The effectiveness of IDFA in an ecommerce set-up depends on several factors, primarily the responsiveness of the target audience to ads and the overall performance of the ad campaign. By using A/B testing or tweaking ad content, placement, and timing, businesses can improve their marketing strategies and, therefore, enhance the effectiveness of IDFA.

How can IDFA be improved?

What is IDFA’s relationship with other metrics?

IDFA intersects with various ecommerce metrics to provide meaningful insights. For instance, it can couple with metrics like Brand Lift to evaluate an advertisement’s impact on the brand perception. Similarly, it can correlate with the Conversion Rate to assess the effectiveness of an advertising campaign in converting prospects into customers.

Free essential resources for success

Discover more from Lifesight

  • The Future of Retail Growth scaled - Lifesight

    Published on: October 17, 2025

    The Future of Retail Growth: How Unified Measurement Powers Profitability

    Presented at Advertising Week New York 2025

  • Incrementality Adjusted Attribution

    Published on: September 3, 2025

    Incrementality-adjusted Attribution: Boost True ROAS Accuracy

    Incrementality-adjusted Attribution blends lift and attribution to deliver true iROAS, bridging marketing dashboards with CFO-trusted ROI.

  • Best Incrementality Testing Tools

    Published on: September 2, 2025

    6 Best Incrementality Testing Tools in 2025 [UPDATED]

    The Best 6 incrementality testing tools for 2025 to prove causal lift, optimize ad spend, and improve ROI with geo tests, MMM & attribution.