Privacy mode, sometimes informally referred to as "porn mode", or "private browsing" is a term that refers to privacy features in some web browser

Web browser

A web browser is a software application for retrieving, presenting, and traversing information resources on the World Wide Web. An information resource is identified by a Uniform Resource Identifier and may be a web page, image, video, or other piece of content...

s. Historically speaking, web browsers store information such as browsing history, images, videos and text within cache

Web cache

A web cache is a mechanism for the temporary storage of web documents, such as HTML pages and images, to reduce bandwidth usage, server load, and perceived lag...

. In contrast, privacy mode can be enabled so that the browser does not store this information for selected browsing sessions. This allows a person to browse the Web without storing local data that could be retrieved at a later date. It is of note that this offers virtually no privacy protection beyond the local level. For example, it is still possible to identify frequented websites by associating the IP address

IP address

An Internet Protocol address is a numerical label assigned to each device participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing...

 with the user on the server end. Privacy mode will also disable the storage of data in cookies

HTTP cookie

A cookie, also known as an HTTP cookie, web cookie, or browser cookie, is used for an origin website to send state information to a user's browser and for the browser to return the state information to the origin site...

 or Flash cookies

Local Shared Object

Local Shared Objects , commonly called flash cookies are pieces of data that websites which use Adobe Flash may store on a user's computer...

.

The Mozilla Foundation

Mozilla Foundation

The Mozilla Foundation is a non-profit organization that exists to support and provide leadership for the open source Mozilla project. The organization sets the policies that govern development, operates key infrastructure and controls trademarks and other intellectual property...

 made a study about the user behavior when the feature is switched on and how long the session lasts. The results were that most sessions last only about 10 minutes, though there are periods where activation increases; usually around 11am to 2pm, 5pm, between 9pm and 10pm, and a minor peak about an hour or two after midnight.

History

The earliest reference to the term was in May 2005 and used to discuss the privacy features in the Safari

Safari (web browser)

Safari is a web browser developed by Apple Inc. and included with the Mac OS X and iOS operating systems. First released as a public beta on January 7, 2003 on the company's Mac OS X operating system, it became Apple's default browser beginning with Mac OS X v10.3 "Panther". Safari is also the...

 browser bundled with Mac OS X Tiger. The feature has since been adopted in other browsers, and led to popularisation of the term in 2008 by mainstream news outlets and computing websites when discussing beta versions of Internet Explorer 8

Internet Explorer 8

Windows Internet Explorer 8 is a web browser developed by Microsoft in the Internet Explorer browser series. The browser was released on March 19, 2009 for Windows XP, Windows Server 2003, Windows Vista, Windows Server 2008, and Windows 7. Both 32-bit and 64-bit builds are available...

. However, privacy modes operate as shields because browsers typically do not remove all data from the cache after the session. Plugins, like Silverlight

Microsoft Silverlight

Microsoft Silverlight is an application framework for writing and running rich Internet applications, with features and purposes similar to those of Adobe Flash. The run-time environment for Silverlight is available as a plug-in for web browsers running under Microsoft Windows and Mac OS X...

, are able to set cookies that will not be removed after the session. Internet Explorer 8 also contains a feature called InPrivate Subscriptions, an RSS

RSS

-Mathematics:* Root-sum-square, the square root of the sum of the squares of the elements of a data set* Residual sum of squares in statistics-Technology:* RSS , "Really Simple Syndication" or "Rich Site Summary", a family of web feed formats...

 web feed

Web feed

A web feed is a data format used for providing users with frequently updated content. Content distributors syndicate a web feed, thereby allowing users to subscribe to it. Making a collection of web feeds accessible in one spot is known as aggregation, which is performed by an aggregator...

 with sites approved for use with InPrivate browsing.

The release of Adobe Flash Player

Adobe Flash Player

The Adobe Flash Player is software for viewing multimedia, Rich Internet Applications and streaming video and audio, on a computer web browser or on supported mobile devices. Flash Player runs SWF files that can be created by the Adobe Flash authoring tool, by Adobe Flex or by a number of other...

 10.1 supports privacy mode in Chrome, Firefox, Internet Explorer and Safari.

Supported browsers

Privacy mode is known by different names in different browsers:

Date	Browser	Synonym	Latest stable
	Safari Safari (web browser) Safari is a web browser developed by Apple Inc. and included with the Mac OS X and iOS operating systems. First released as a public beta on January 7, 2003 on the company's Mac OS X operating system, it became Apple's default browser beginning with Mac OS X v10.3 "Panther". Safari is also the...  2.0	Private Browsing
	Google Chrome Google Chrome Google Chrome is a web browser developed by Google that uses the WebKit layout engine. It was first released as a beta version for Microsoft Windows on September 2, 2008, and the public stable release was on December 11, 2008. The name is derived from the graphical user interface frame, or...  1.0	Incognito
	Arora Arora (browser) Arora is a free and open source lightweight cross-platform web browser. It runs on Linux, Mac OS X, Windows, FreeBSD, OS/2, Haiku, and any other platforms supported by the Qt toolkit....  0.5	Privacy Mode
	Internet Explorer 8 Internet Explorer 8 Windows Internet Explorer 8 is a web browser developed by Microsoft in the Internet Explorer browser series. The browser was released on March 19, 2009 for Windows XP, Windows Server 2003, Windows Vista, Windows Server 2008, and Windows 7. Both 32-bit and 64-bit builds are available...	InPrivate Browsing
	Mozilla Firefox 3.5 Mozilla Firefox 3.5 Mozilla Firefox 3.5 is a version of the Firefox web browser released in June 2009, adding a variety of new features to Firefox. Version 3.5 was touted as being twice as fast as 3.0...	Private Browsing
	Shiira Shiira Shiira is an open source web browser for the Mac OS X operating system. According to its website, the goal of Shiira was "to create a browser that is better and more useful than Safari". Shiira uses WebKit for rendering and scripting.Shiira Project was led by Makoto Kinoshita. The latest release...  2.3	Private Browsing
	Opera 10.50	Private Tab / Private Window
	Maxthon Maxthon Maxthon is a free web browser for Microsoft Windows. The latest release, Maxthon 3, supports both the Trident and the WebKit rendering engines.... 2.5.12.4534	Private Browsing

External links

• Mozilla Specification for Private Browsing