This allows the user to browse the Web without leaving traces such as local data that can later be retrieved. One major feature of private browsing is disabling data storage through cookies, which is a way for websites to track and record a user's activities.
Private browsing is a mode where all the privacy features of the Web browser are activated without having to manually set them individually, such as setting cookies to off and clearing the browsing history. When using private browsing mode none of this data is stored. It became widely available in May 2005, when it was included in the Safari Browser which came with Mac OS X Tiger.