Glossary /
ATT
Efficiency & cost
ATT
Apple's opt-in prompt that decides whether an app can access the device's advertising identifier.
Attribution & Measurement
Unit Economics
Data Governance & Nomenclature
Creative & Delivery
Audiences & Targeting
Mobile & Privacy
ATT (App Tracking Transparency) is Apple's policy, enforced since iOS 14.5, requiring apps to show an opt-in prompt before accessing the IDFA or tracking users across other companies' apps and sites.
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What is ATT?
ATT is the consent gate. Any app that wants to use the IDFA — Apple's per-device advertising identifier — or otherwise track a user across other companies' properties must first show Apple's standardized prompt: 'Allow [App] to track your activity across other companies' apps and websites?' If the user declines, the IDFA returns all zeros and that user is effectively un-trackable for cross-app attribution. Opt-in rates landed low — commonly cited in the 20–40% range depending on app and region — which gutted the deterministic, user-level attribution that mobile advertising had relied on. This is the event that pushed the industry toward SKAN, modeled conversions, and aggregated measurement. ATT governs access; it doesn't itself attribute anything. But because it collapsed IDFA availability, it's the root cause of nearly every post-iOS-14.5 measurement change marketers feel.
How ATT differs across ad platforms
Apple
Apple owns and enforces ATT. It dictates the prompt wording, when it can appear, and the penalty for non-compliance (App Store rejection). Apple positions ATT as a privacy feature; its own ad products operate under different rules, a frequent point of industry friction.
Meta
Hit hardest. Meta's iOS performance and signal quality dropped sharply post-ATT because so much of its optimization depended on user-level cross-app data. Meta now leans heavily on SKAN, the Conversions API, and modeled conversions to fill the gap.
Affected but less severely, partly because much of Google's inventory is its own logged-in surfaces (Search, YouTube) where it relies less on the IDFA. Google still adapted iOS App campaigns to lean on SKAN and modeling.
Common ATT misconceptions
ATT bans all tracking on iOS.
It doesn't. ATT requires consent for cross-app tracking via the IDFA. First-party data, contextual signals, SKAN attribution, and on-device measurement all still work. ATT gates one specific identifier and one specific behavior.
ATT and SKAN are interchangeable terms.
ATT is the consent prompt that controls IDFA access. SKAN is the separate attribution framework that runs regardless of consent. They were introduced together but solve different problems — ATT restricts, SKAN measures within the restriction.
Related Terms
Frequently Asked Questions
What is ATT in simple terms?
ATT is the pop-up iPhone users see asking whether an app can track them across other companies' apps and websites. If they tap 'Ask App Not to Track,' the app loses access to the device's advertising ID — so most cross-app ad measurement for that user goes dark.
How does ATT work?
Why does ATT differ across ad platforms?
How does Clarisights report on ATT?
Attribution & Measurement
Unit Economics
Data Governance & Nomenclature
Creative & Delivery
Audiences & Targeting
Mobile & Privacy
ATT (App Tracking Transparency) is Apple's policy, enforced since iOS 14.5, requiring apps to show an opt-in prompt before accessing the IDFA or tracking users across other companies' apps and sites.
?
?
What is ATT?
ATT is the consent gate. Any app that wants to use the IDFA — Apple's per-device advertising identifier — or otherwise track a user across other companies' properties must first show Apple's standardized prompt: 'Allow [App] to track your activity across other companies' apps and websites?' If the user declines, the IDFA returns all zeros and that user is effectively un-trackable for cross-app attribution. Opt-in rates landed low — commonly cited in the 20–40% range depending on app and region — which gutted the deterministic, user-level attribution that mobile advertising had relied on. This is the event that pushed the industry toward SKAN, modeled conversions, and aggregated measurement. ATT governs access; it doesn't itself attribute anything. But because it collapsed IDFA availability, it's the root cause of nearly every post-iOS-14.5 measurement change marketers feel.
How ATT differs across ad platforms
Apple
Apple owns and enforces ATT. It dictates the prompt wording, when it can appear, and the penalty for non-compliance (App Store rejection). Apple positions ATT as a privacy feature; its own ad products operate under different rules, a frequent point of industry friction.
Meta
Hit hardest. Meta's iOS performance and signal quality dropped sharply post-ATT because so much of its optimization depended on user-level cross-app data. Meta now leans heavily on SKAN, the Conversions API, and modeled conversions to fill the gap.
Affected but less severely, partly because much of Google's inventory is its own logged-in surfaces (Search, YouTube) where it relies less on the IDFA. Google still adapted iOS App campaigns to lean on SKAN and modeling.
Common ATT misconceptions
ATT bans all tracking on iOS.
It doesn't. ATT requires consent for cross-app tracking via the IDFA. First-party data, contextual signals, SKAN attribution, and on-device measurement all still work. ATT gates one specific identifier and one specific behavior.
ATT and SKAN are interchangeable terms.
ATT is the consent prompt that controls IDFA access. SKAN is the separate attribution framework that runs regardless of consent. They were introduced together but solve different problems — ATT restricts, SKAN measures within the restriction.
Frequently Asked Questions
What is ATT in simple terms?
ATT is the pop-up iPhone users see asking whether an app can track them across other companies' apps and websites. If they tap 'Ask App Not to Track,' the app loses access to the device's advertising ID — so most cross-app ad measurement for that user goes dark.
How does ATT work?
Why does ATT differ across ad platforms?
How does Clarisights report on ATT?
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