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...