How to block Third Party (tracking/advertising) cookies in IE:
http://privacy.getnetwise.org/browsing/tools/ie6/block3--------------------------------------------------------------------------------
http://www.lifehacker.com/software/firefox...eaks-209941.phpStarting in Firefox 2.0, The option to block third-party cookies has been removed from the user interface [1]. Firefox 2.0 users who wish to limit allowed cookies to those set by the originating website can use about:config to modify the preference network.cookie.cookieBehavior to "1"
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http://www.ghacks.net/2006/11/03/how-to-di...ies-in-firefox/http://www.ghacks.net/category/browsing/firefox/The developers of Firefox removed the option to disable third party cookies in firefox 2.0 stating the reason that it was not possible to block all third party cookies with this function. Third Party Cookies are mainly cookies that track user behavior, the big ad networks for instance like to use them a lot. There are basically two options to disable third party cookies in Firefox.
The first would be to disable it manually by opening about:config from the address bar. Search for network.cookie.cookieBehavior and take a look a the value. If it is set to 0 you accept all cookies, 1 means you only accept cookies from the same server, 2 means you disable all cookies. Setting it to 1 has the same effect that the option in the old firefox browsers had: it disables third party cookie
I promised a second option. You could install a add-on as well that blocks third party cookies. One of the many extensions that does that is called CookieSafe. This one for instance makes it possible to disable all cookies and allow them only for specific sites (whitelist). There is no need that most sites store cookies when you are visiting them unless you have an account on that site.
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http://en.wikipedia.org/wiki/HTTP_cookiePrivacy and third-party cookies
Cookies have some important implications on the privacy and anonymity of Web users. While cookies are only sent to the server setting them or one in the same Internet domain, a Web page may contain images or other components stored on servers in other domains. Cookies that are set during retrieval of these components are called third-party cookies.
Advertising companies use third-party cookies to track a user across multiple sites. In particular, an advertising company can track a user across all pages where it has placed advertising images or web bugs. Knowledge of the pages visited by a user allows the advertisement company to target advertisement to the user's presumed preferences.
The possibility of building a profile of users has been considered by some a potential privacy threat, even when the tracking is done on a single domain but especially when tracking is done across multiple domains using third-party cookies. For this reason, some countries have legislation about cookies.
The United States government has set strict rules on setting cookies in 2000 after it was disclosed that the White House drug policy office used cookies to track computer users viewing its online anti-drug advertising to see if they then visited sites about drug making and drug use. In 2002, privacy activist Daniel Brandt found that the CIA had been leaving persistent cookies on computers for ten years. When notified it was violating policy, CIA stated that these cookies were not intentionally set and stopped setting them.[8] On December 25, 2005, Brandt discovered that the National Security Agency had been leaving two persistent cookies on visitors' computers due to a software upgrade. After being informed, the National Security Agency immediately disabled the cookies.[9]
The 2002 European Union telecommunication privacy Directive contains rules about the use of cookies. In particular, Article 5, Paragraph 3 of this directive mandates that storing data (like cookies) in a user's computer can only be done if: 1) the user is provided information about how this data is used; and 2) the user is given the possibility of denying this storing operation. However, this article also states that storing data that is necessary for technical reasons is exempted from this rule. This directive was expected to have been applied since October 2003, but a December 2004 report says (page 38) that this provision was not applied in practice, and that some member countries (Slovakia, Latvia, Greece, Belgium, and Luxembourg) did not even implement the provision in national law. The same report suggests a thorough analysis of the situation in the Member States.
[edit] Drawbacks of cookies