AdSense and cookies

AdSense and cookies

In the near future — 8 April 2009 — Google will be implementing something called “DoubleClick DART cookies”, which is a fancy name for a little text file stored on your computer.

What this cookie does may worry some of you. Whenever you visit a website with Google ads on it, the cookie records this, building up a picture of what you’re interested in. So if, for example, you visit lots of websites about sport, Google will notice this and serve you with more sport-related ads.

That really goes beyond what cookies are really supposed to do; in fact, when cookies were first invented, they were hobbled to prevent this from even being possible. Basically, a cookie set by can only ever be read by, so it shouldn’t be possible to track what websites you’re visiting.

But this new cookie is set not by, but by Google AdSense itself. Because Google AdSense knows which ads it’s serving to which website, this makes it possible to track your movements through the internet on any site served by Google AdSense. That’s a privacy concern.

On the other hand, it isn’t quite as bad as it might be. Cookies still can’t steal your private information, like your name, address, telephone number and so on. The information collected is difficult to match up to an individual person. You certainly won’t get spam or junk mail, but you will get ads served on the basis not of what’s actually on the website you’re currently looking at, but what kind of sites you habitually visit.

Luckily, Google have offered a way to opt out of this scheme. If you do feel uncomfortable about this new development, go to Google’s Privacy Center and click on the nice big blue button at the top of the page.