How to Enable Private Browsing in Firefox for Linux, Mac, and Windows

firefox private browsing
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This article is only intended for users running the Firefox Web browser on Linux, Mac OS X or Windows operating systems.

Beginning with version 29, Mozilla completely redesigned the look and feel of its Firefox browser. This fresh coat of paint included some modifications to its menus, where many popular everyday features are found - one being Private Browsing mode. While active, Private Browsing mode ensures that you can surf the Web without leaving any tracks behind on the hard drive such as cache, cookies and other potentially sensitive data.

This functionality is especially useful when browsing on a shared computer such as those found at school or work.

This tutorial explains Private Browsing mode as well as how to activate it on the WindowsMac, and Linux platforms.

First, open your Firefox browser. Click on the Firefox menu, located in the upper right-hand corner of your browser window and represented by three horizontal lines. When the pop-out menu appears, click on the New Private Window option. A new browser window should now be open. Private Browsing mode is now active, noted by the purple and white "mask" icon located in the upper right-hand corner.

During a Private Browsing session, most data components normally stored on your local hard drive are deleted as soon as the active window is closed. These private data items are described in detail below.

  • Browsing History: Firefox stores a log of all websites that you've visited, utilizing this data in the Awesome Bar's address list, the History menu, and the list of browsing history displayed in the Library window. Private Browsing mode ensures that these records are not saved on your hard drive or elsewhere.
  • Cache and Offline Web Content: Occasionally referred to as temporary Internet files, a cache is comprised of images, multimedia files, as well as entire Web pages which are stored locally and utilized to speed up load times on subsequent visits. In addition to cache, some websites store specific content intended for offline use.
  • Cookies: Small text files containing user-specific settings and other information unique to you and your browsing experience, cookies are saved locally by most websites. Login session status, user preferences, and other customized data can be stored within a cookie file.
  • Download History: A record of the websites that you've visited is not the only history that Firefox retains at the end of a standard browsing session. The file name, origination URL, size, and date of download for all files obtained via the browser are also saved for future reference. Details of any file downloaded while in Private Browsing mode are not stored.
  • Form and Search Bar AutoComplete Data: Some personal data entered into Web forms, such as name and address, as well as keywords entered into Firefox's Search bar, is stored locally by the browser. It is then utilized by its AutoComplete feature during future browsing sessions. None of this information is retained while Private Browsing mode is active.
  • Saved Passwords: One of the most widely used private data components that Firefox stores, and perhaps one of the most vulnerable from a security standpoint, your personal passwords are utilized for email, banking, and a litany of other websites that require login credentials for access.

    Although Private Browsing mode provides a welcome security blanket for those users worried about leaving tracks behind, it is not a catch-all solution when it comes to sensitive data being stored on the hard drive. For example, new bookmarks created during a Private Browsing session will remain intact after the fact. Also, while download history may not be stored while browsing privately, the actual files themselves are not deleted.

    The previous steps of this tutorial detailed how to open a new, empty Private Browsing window. However, you may want to open a specific link from an existing Web page in Private Browsing mode.

    To do so, first, right-click on the desired link. When Firefox's context menu is displayed, left-click on the Open Link in New Private Window option.