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Comment by shostack | Hacker News Reader

Who said the browser has to report everything you do online to be of value.

I don't claim to know anything about how Chrome works, so could be completely wrong in this, but my sense is that it is part of a broader desire to tie together tracking across all devices. Cracking that nut is very difficult from an analytics perspective, and having people logged in to Chrome across all devices provides a very convenient GUID for matching against AdSense units, DFA tags, GA tags, etc.

So the value in this play is not necessarily in knowing everything you do online, but simply knowing that you are who you are regardless of device or Chrome instance. That means data about you is consistent, and can feed into the broader targeting algorithms to serve you the right ad, at the right place, at the right time.

Again, I don't know what data Chrome makes available to Google's ad services, so please tell me if I am in fact incorrect here.

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> Again, I don't know what data Chrome makes available to Google's ad services, so please tell me if I am in fact incorrect here.

If you read the very detailed Chrome privacy policy (https://www.google.co.uk/chrome/browser/privacy/), you will see that it does nothing different to other browsers here (each server sees your IP address, cookies, etc). It does not send any form of uniquely identifiable ID with every request. Only some very specific cases (offline drive, google wallet, DRM auth, etc) send your signed-in userid, which they need in order to work at all.

Please read the privacy policy. People put a lot of time and effort into writing it and it answers all your questions.

I have read it, and respectfully disagree that it sufficiently addresses my very specific point.

I see a section in the link you provided that reads:

> "Chrome OS may send a non-unique promotional tag to Google periodically (including during initial setup) and when performing searches with Google."

Sure Chrome may not be sending a GUID with every request. That wasn't my point. To clarify, my point was that Google has a GUID (your Google account, and likely other forms of ID) that identify you pretty clearly across devices/Chrome instances. I saw nothing in the policy you linked that said Google AdSense and other Google ad services (DoubleClick tags, GA, etc.) do not use that information to link identities across devices for purposes of tracking.

The AdWords and GA teams have rolled out significant advances in cross-device tracking over the past year or two, including new metrics and reports in the respective platforms. It seems pretty obvious to me that this is a data point that is factored into making that link.

But again, I'd love to be proven wrong if I missed a section of your link that explicitly says otherwise.

That bit is about Chrome OS (ie, a chromebook), not Chrome itself. The bit about it being "non-unique" means it's not a GUID - other people's devices will send the same tag. It does not identify you.

> To clarify, my point was that Google has a GUID (your Google account, and likely other forms of ID) that identify you pretty clearly across devices/Chrome instances.

I think the privacy policy is quite clear that Chrome does nothing here that other browsers don't do. Obviously if you have a Google cookie from signing in to the website then that's going to identify you pretty clearly, but that's just how cookies work, and would be exactly the same in any other browser. I'd like to specifically direct your attention to the first three paragraphs of the policy, and in particular:

"If you use Chrome to access other Google services, such as using the search engine on the Google homepage or checking Gmail, the fact that you are using Chrome does not mean that Google will receive any special or additional personally identifiable information about you."

> I saw nothing in the policy you linked that said Google AdSense and other Google ad services (DoubleClick tags, GA, etc.) do not use that information to link identities across devices for purposes of tracking.

I wouldn't expect to find any information about how AdSense works in the Chrome policy. The privacy policy for ads is over here and discusses this topic: http://www.google.co.uk/policies/technologies/ads/

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