Comment by antpls | Hacker News Reader

Comment by antpls | Hacker News Reader

Today I browsed Google from my desktop PC about "Gundam" (the japonese anime) for about 1 hour. Pretty niche topic.

Then when I was done, I closed all browser tabs, I unlocked my smartphone to check Instagram, and the second ads I get is a Gundam ad. I have no idea how my shadow "desktop" ad profile and shadow "mobile" ad profile matched. I share no accounts between my desktop and my smartphone :

  - I use different Google accounts on my phone and desktop (although I occasionally log in one or the other in private tabs)
  - The internet connections are different : 4G for phone, fiber for desktop
  - On desktop, I use Chromium with Ad block Plus
  - I do not use facebook nor instagram on my desktop PC

So how the f. did Instagram know about my Gundam browsing on desktop.

This must stop.

If you log in different google accounts in private tabs, then any browser fingerprinting would immediately link them.

Also, it's plausible that one of your contacts has your phone number connected with the email of your desktop google account.

I think Instagram can usually figure it out from the Minovsky Particles given off by your PC for that short bit of time.

LiveRamp connects all the “anonymous” identifiers together for a household.

Third party SDKs also report your location to these services[0], which makes it trivial to track your phone to your location (or they could just buy that info directly from the carrier).

Your home ISP's assigned IP is also in a database with your name and a unique identifier. So it doesn't matter what adblocking you use, they still know where the hits are coming from.

All this data is traded around the ad "ecosystem" and integrated real-time, so it can be milliseconds from action to ad-impression.

[0] https://www.nytimes.com/interactive/2019/12/19/opinion/locat...

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