Blurs

Ad networks don’t usually “know you” in a single, direct way. They assemble a stitched-together identity from many weak signals collected across different websites.  Think of it less like a passport and more like reconstructing the same person from repeated patterns of behaviour and device traits. Here’s how that identity merging actually works. 1) The shared tracking script ecosystem (the backbone) Most websites don’t run their own tracking from scratch. They embed third-party scripts from large ad platforms and analytics providers. When you visit Site A and Site B, both might load the same tracking code from the same company. That means: • The same tracking infrastructure sees both visits • It can compare signals across millions of sites • It builds a cross-site activity graph So even if the websites are unrelated, the tracker is the common observer linking them. 2) Cookie syncing (classic cross-site identity linking) Historically, ad networks used third-party cookies to recognis...

Apple’s privacy changes—especially App Tracking Transparency (ATT)—didn’t stop tracking so much as break one of the main pipes used to connect identity across apps.  That forced ad networks (including Meta and others) to rebuild their systems around weaker, more indirect signals. Here’s what actually changed. 1) What ATT actually did App Tracking Transparency requires apps on iOS to ask: “Allow this app to track your activity across other companies’ apps and websites?” If the user says no, the app cannot access the IDFA (Identifier for Advertisers). That matters because IDFA used to be: • a stable device-level advertising ID • shared across apps • resettable but persistent enough for long-term tracking So ATT effectively: • cut off the easiest cross-app identity connector on iPhones 2) What got broken (significant disruption) A) Cross-app tracking collapsed Before ATT: • App A knows you installed App B • Both apps can share the same advertising ID • Ad networks stitch behaviour to...