I HIGHLY suggest everyone use this addon or something similar. The best explanation can be found on the addon’s homepage:
Why should I use TACO?
A large number of commercial companies now track users’ browsing across the web, in order to profile them, and then serve them targeted advertising. This so called behavioral advertising is a threat to the average user’s privacy.
An industry group, The Network Advertising Initiative, provides an easy way for users to opt-out of the tracking performed by its member companies. Users can visit a single web page, and then easily set opt-out web cookies for all of the NAI members advertising networks. privacychoice.net has a cool wizard that will set cookies for a bunch of other non-NAI member advertising networks too.
The problem with this is that the moment a user clears his or her cookies, they also lose the opt-out cookies. Regularly clearing browser cookies, or better, setting the browser to erase them all at the end of a session, is a recommended practice. Unfortunately, by doing this, users are then required to re-visit the NAI and privacychoice.net opt-out page each time they start browsing the web. This is obviously not a reasonable thing to expect.
Google recently announced that it would be engaging in the large scale collection and use of targeted advertising information. However, in addition to offering an opt-out cookie, the company has also developed a Firefox add-on, so that users can maintain the opt-out cookies, even if they regularly erase the other cookies.
Google should be commended for releasing such a useful privacy enhancing technology (even though their use of targeted advertising is creepy, and should be prohibited by the FTC). If only this add-on could be used to protect people from the prying eyes of the other advertising networks…..
If you are not using Firefox I HIGHLY suggest you start! Get it here