Private Browsing in Firefox

private browsingIn this era of Internet, when there is a growing concern over privacy and security issues, Firefox has rightly introduced the Private Browsing mode starting from its version 3.5.

If you have been using some earlier versions of Firefox, we strongly recommend that you immediately upgrade your browser to the latest version to address the security concerns.

Firefox 3.5 allows you to enter private browsing mode by going to Tools->Start Private Browsing, and you will enter into a private mode and there will be no records in the browser history about what sites you have visited in this session.

This is what the FAQ section of the Firefox 3.5 says about this feature.

Q: How does the Private Browsing mode work in Firefox 3.5?
A: Suppose you’re shopping for a surprise gift, so you don’t want the sites you’ve been viewing stored in your browser’s history. You can enter private browsing mode by going to Tools->Start Private Browsing. A simple dialog screen confirms you’ve entered this mode and nothing you encounter on the Web will be recorded from that moment on: none of the websites you visit and none of the cookies you collect will be saved. Exit private browsing mode through the Tools menu again and you’re back to normal browsing.

Q: What if I forget to enter Private Browsing mode and want Firefox to forget the website I just visited?
A: Firefox 3.5 includes a new feature – Forget this Site – where you can remove every trace of that site from your browser—no questions asked! Open the History Sidebar from the View menu, select a website and then select Forget This Site from the right-click menu.

You can also clear all your private data or just your activity over the past few hours with a few quick clicks with Firefox 3.5’s improved Clear Recent History feature. With Firefox 3.5 you have full control over what to delete and that information is gone for good—on your own computer or the one at your local library. You can find this feature in the Tools menu.

But, does Firefox really makes your session private? Does it deletes all traces of the websites you have visited from all places in your browser.

Surprisingly not.

As found by Michael on, there are lots of traces still remaining there. There are cookies left in your browser. There are flash cookies, which does not get cleared.

If you want to experience a true private browsing and clear all traces, then you can consider to use some sandbox application like SandBoxie.