Apple's App Tracking Transparency (2021)
Apple required apps to get opt-in permission before tracking users across other apps via the Identifier for Advertisers (IDFA). Most users declined, cutting off the precise cross-app tracking mobile advertisers relied on.
Mobile ad attribution became unreliable. Advertisers lost visibility into which campaigns drove installs and revenue.
The industry shifted from deterministic tracking to probabilistic models and ML-based prediction. Companies like AppNava emerged to fill the gap.
AppNava's entire market exists because ATT broke deterministic attribution. The startup's ML models predict user value from early behavior instead of tracking individual users.
