Blurs

Google and Meta don’t “magically” know your phone and laptop are yours.  They build that link by stitching together multiple overlapping signals until the probability becomes very high. Here we’ll break down how each company typically does it in practice. 1) The core idea: identity graphs Both Google and Meta Platforms build what’s called an identity graph. Instead of: “This is user X” They store: • devices • browsers • app sessions • login events • IP history • behavioural patterns ..and connect them with confidence scores like: “These devices likely belong to the same person or household” 2) The strongest link: login accounts Google If you’re signed into: • Gmail • YouTube • Chrome • Android …you’ve essentially provided a hard identity anchor. Once logged in: • laptop browser ID • phone app ID • tablet session ..all get tied to the same Google Account automatically. Even if you switch devices, the login connects them instantly. Meta Same idea with: • Facebook • Instagram • WhatsA...

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...