Google spy you with AdSense
Some people already suspected it, but it's official: the AdSense ads follow you from one site to another to know your interests
It was in an e-mail sent today to all AdSense publishers «Introducing advertising targeted by user interest».
Normally, a cookie can not be shared by multiple sites. The rules of the browsers prevent to read the cookie from another domain. But as AdSense ads call a page located at Doubleclick.net (company acquired by Google in 2007 and now used for AdSense), the cookie is placed by ad.doubleclick.net and not by each site showing the ads.
This allows to follow you when you move from site to site, to know what search terms led you to a site, and even if the content of the site doesn't interest you, Google will offer you advertising closest to your expectations!
As a publisher, this feature is probably a bonus. But as a web surfer, caution should be exercised. Especially if a computer is shared by several persons.
How Google may know that the little child, that takes his old brother's computer after school, is not one that has surfed porn sites all afternoon? And it would be inappropriate to offer him advertising "targeted by centers of interest"?
How to get rid of it?
If you do not want to be followed everywhere you go on the web, Google offers to disable this cookie called "DART" (multi-domain). But how does it hold your choice? With a new cookie!
Google offers to install an extension to disable definitely the cookie on your browser. However there is a simpler method, that works in all browsers: to ban cookies for *.doubleclick.net areas. See the privacy options in your browser.
Or even more draconian, the very powerful extension for Firefox AdBlock or integrated blocker in Opera. Once the ads blocked, obviously avoids their cookies.
Personally, I chose to clean all cookies when closing Firefox or Opera, except some sites set as exceptions. This allows you to surf without problem, while still providing some privacy on each browser closure.
The great Google's bright idea is to show itself as a nice company, providing a lot of free services. Subject already discussed here for Chrome.
The trouble is, of course, its omnipresence in the lives of many surfers: emails, documents, maps, research... some people show Google absolutely all their privacy. And because of the webmasters using Google Analytics, it even knows if you buy in a shop after having clicked on an advertisement.