Discussion of article How to config Firefox for Private Browsing?:
QuotePrivacy while surfing the web is important to most people, to the point that the majority of web browsers offer some type of private mode providing the ability to cover your tracks throughout a browsing session. In Mozilla Firefox, Private Browsing can be activated at any time by following the steps below.
Private Browsing doesn't mean your activities on the web are completely anonymous. Your ISP or employer can still monitor which sites you visit, and some of your actions on said sites, while website owners may also have some insight into information like your IP address and general location.