

On the Web's Cutting Edge, Anonymity in Name Only - helwr
http://online.wsj.com/article/SB10001424052748703294904575385532109190198.html?mod=WSJ_hpp_LEFTTopStories

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drinian
Seems like a good time to resurrect /etc/hosts as killfile.
<http://someonewhocares.org/hosts/>

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drenei
Oh privacy, I knew you well. Does anyone have insights into any specific
methods [x+1] would use?

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gyardley
It's just standard-issue behavioral targeting. Dozens of firms do this - I
wouldn't describe what [x+1] is doing as exceptional or new.

While all of this is harmless, you can block all the trackers by installing
Ghostery (ghostery.com) - works with Firefox and Chrome.

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RK
So are they reading the cookies you have from other sites?

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gyardley
No, a domain can't read cookies set by another domain.

Here's how it works: a publisher (eg. 'travel.com') will place a snippet of JS
or an image from a tracker (eg. 'tracker.com') on its site - anything to
initiate a HTTP request. The HTTP response from 'tracker.com' will set a
'tracker.com' cookie in your browser. This cookie will contain a unique
identifier, which links to a backend database at 'tracker.com', which will now
contain the fact that you visited 'travel.com'. Sometimes 'travel.com' will
use JS to add parameters to the HTTP request to 'tracker.com', to pass things
like gender or age or location, should they know that about you. This
information is also added to the database at 'tracker.com', keyed to the
unique identifier in your cookie.

You'll then go to another site, which will make a request for an
advertisement. The request might be directly to 'tracker.com', or it might be
to another domain which will return JS which will then force an HTTP request
to 'tracker.com'... there could be many redirects, but an HTTP request to
'tracker.com' is involved, which automatically contains the unique identifier
in your cookie.

'Tracker.com' then uses that unique ID to look up what it knows about you,
potentially supplements that with location based off your IP address, and
potentially appends some guesses about demographic info made from the content
of the site you're visiting and the type of folks that tend to live in your
ZIP code. It then uses all of this (or passes all of this on to another party)
to select a related advertisement. That's why you see ads for cars after
visiting car sites, and ads for travel after visiting travel sites.

There's nuances, of course, but that's the gist of it.

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fdb
Wow, I visited the Capital One page for myself and was pretty amazed with the
results: interests where right aligned.

I got different pages when switching browser (although you have to clear
cookies/flash cookies), and also different credit card proposals (some student
cards for you in Chrome? Or rather some "serious" cards in Internet Explorer)

You can find the tracking from the domain .edge.ru4.com. It does contain a
wealth of information, although I have yet to find the identifier for "my"
Nielsen Market Segment. The segments are here:

[http://www.claritas.com/MyBestSegments/Default.jsp?ID=30&...](http://www.claritas.com/MyBestSegments/Default.jsp?ID=30&SubID=&pageName=Segment%2BLook-
up)

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5teev
Does this mean if I'm an undesirable customer, they'll stop showing me ads
altogether?

