As you browse the web, Firefox remembers lots of information for you: sites you've visited, files you've downloaded, and more. There may be times, however, when you don't want other users on your computer to see this information, such as when shopping for a birthday present.
Private Browsing allows you to browse the Internet without saving any information about which sites and pages you’ve visited. This article explains what information is not saved when in Private Browsing and gives you step-by-step instructions for using it.
There are two ways to open a new Private Window.
There is a setting in the OptionsPreferences window that automatically enables Private Browsing whenever you start Firefox.