Mozilla Firefox: No More Third-Party Cookies

Dennis Faas's picture

Mozilla says it will take steps to stop advertisers from violating Firefox user privacy. But advertisers have labeled the move an act of war.

Mozilla has announced that it will change the Firefox browser so that third-party cookies -- such as those from advertisers -- are blocked by default.

Cookies are small text files created by websites and stored on your computer.

Cookies Key to Website Advertising

In many cases cookies help the website visitor. For example, a cookie might store your username to make logging in faster, or it could store your ZIP code so you can instantly get customized movie listings or weather forecasts from a site without having to type your details in every time you visit.

However, storing and viewing cookies can allow sites to track your Internet activity. Many sites use cookies to choose suitable advertisements for the website visitor.

Such tracking cookies are particularly controversial when they are issued by third-party advertisers rather than the actual website you visit. (Source:

'Do Not Track' Cookie Solution Limited

Both website creators and browser developers have worked on ways to deal with this issue. For example, they've developed a "do not track" signal that involves the browser telling sites the user doesn't want to be tracked by third-party cookies.

The problem is that these solutions rely on advertisers agreeing to take heed of such signals.

Now, Mozilla has taken a more drastic measure. Starting this summer, Firefox's default setting will be to simply block any cookies that don't come directly from the website the user is visiting.

Safari was the first browser to adopt this policy. However, Mozilla's move is causing bigger waves because Firefox has around four times as many users as Safari.

Advertisers are already protesting the move. A spokesman for the Interactive Advertising Bureau said that making the block a default setting represents "a nuclear first strike against [the] ad industry." (Source:

One argument even goes that blocking cookies could make advertising less appealing and valuable, driving down rates and making it harder for some websites to stay in business.

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