What is Safari ITP and why does it matter for ads?
Intelligent Tracking Prevention caps the lifetime of browser cookies - JavaScript-set cookies can expire in days. Multi-day shopping journeys break apart, so returning buyers look like new visitors and ad platforms under-count conversions.
ITP is Apple's tracking-prevention system in Safari. Its biggest ecommerce effect is limiting how long cookies persist, especially those set by scripts. A shopper who clicks an ad and returns days later to buy no longer matches their original visit.
Safari holds a large share of mobile browsing, and mobile holds a large share of commerce traffic, so the distortion is material. Durable, server-set first-party identifiers and server-side event collection are the standard mitigations.