App Tracking Transparency
Apple's iOS framework requiring apps to get explicit user permission before tracking their activity across other apps and websites.
What App Tracking Transparency means
App Tracking Transparency (ATT) is Apple's privacy framework introduced in iOS 14.5 (April 2021) that requires apps to display a permission prompt before tracking user activity across other companies' apps and websites. The prompt asks users to 'Allow Tracking' or 'Ask App Not to Track.' Industry data shows approximately 75-85% of users opt out of tracking. ATT has had a massive impact on digital advertising — Meta reported a $10 billion annual revenue impact, and the effectiveness of behavioral targeting, retargeting, and conversion measurement on iOS decreased significantly. ATT drove the industry shift toward server-side tracking (CAPI), modeled conversions, probabilistic attribution, and first-party data strategies. For advertisers, ATT compliance means implementing SKAdNetwork for iOS campaign measurement, investing in CAPI, and adjusting attribution windows and reporting expectations.
Related terms
Consent
A user's explicit or implied permission for data collection, processing, or advertising targeting, required by privacy regulations.
Pixel
A piece of code installed on a website that tracks user actions and sends data back to an ad platform for measurement and optimization.
CAPI
Conversions API — a server-side tracking method that sends conversion data directly from the advertiser's server to the ad platform.
SDK
Software Development Kit — code integrated into mobile apps for ad tracking, attribution, and in-app event measurement.