Private browsing

[[File:Private Browsing in Firefox 113.png|thumb|The start page for private browsing mode in [[Firefox]].]] '''Private browsing''' (also known as '''incognito mode''' or '''private mode''') is a feature in most [[web browser]]s that enhances user privacy. In this mode, the browser initiates a temporary [[Session (computer science)|session]] [[Interface segregation principle|separate from]] its main session and user data. The [[Web browsing history|browsing history]] is not recorded, and local data related to the session, like [[HTTP cookie|Cookies]] and [[Web cache]], are deleted once the session ends. The primary purpose of these modes is to ensure that data and history from a specific browsing session do not remain on the device or get accessed by another user of the same device. In [[web development]], it can be used to quickly test displaying pages as they appear to first-time visitors.

Private browsing modes do not necessarily protect users from being [[Web tracking|tracked]] by other websites or their [[Internet service provider]] (ISP). Furthermore, there is a possibility that identifiable traces of activity could be leaked from private browsing sessions by means of the operating system, security flaws in the browser, or via malicious [[browser extension]]s, and it has been found that certain [[HTML5]] [[API]]s can be used to detect the presence of private browsing modes due to differences in behavior. This is usually why some people mistake private browsing for a [[virtual private network]].

==History== [[Apple Inc.|Apple]]'s [[Safari (web browser)|Safari]] browser was one of the first major web browsers to include this feature, first introduced in April 2005.<ref name="lifehack">{{cite web |last=Trapani |first=Gina |author-link=Gina Trapani |date=4 May 2005 |title=Safari's private (porn) browsing mode |url=https://lifehacker.com/safaris-private-porn-browsing-mode-102146 |access-date=2010-04-11 |publisher=[[Lifehacker]]}}</ref> The feature was subsequently adopted by other browsers, leading to the popularization of the term in 2008 by mainstream news outlets and computing websites during discussions about the [[Software release life cycle#Beta|beta]] versions of [[Internet Explorer 8]].<ref name=":0">{{cite web|url=http://blogs.zdnet.com/microsoft/?p=1550|title=Microsoft to roll out more granular 'porn mode' with IE 8|first=Mary Jo|last=Foley|publisher=[[ZDNet]]|access-date=2008-10-04|archive-date=9 October 2008|archive-url=https://web.archive.org/web/20081009103410/http://blogs.zdnet.com/microsoft/?p=1550|url-status=dead}}</ref><ref>{{cite web|url=http://www.redherring.com/Home/24763|title=Microsoft's Internet Explorer 8 Goes 'Porn Mode'|first=Lalee|last=Sadighi|publisher=[[Red Herring (magazine)|Red Herring]]|access-date=2008-10-04|url-status=dead |archive-url=https://web.archive.org/web/20080912040417/http://www.redherring.com/Home/24763|archive-date=2008-09-12}}</ref><ref>{{cite web|url=http://apcmag.com/microsoft_releases_ie8_beta_2.htm|title=Microsoft releases IE8 beta 2: MS porn mode included|first=Angus|last=Kidman|publisher=[[APC (magazine)|APC]]|access-date=2008-10-04}}</ref> [[Adobe Flash Player]] 10.1 started respecting browser settings and private browsing modes in relation to storing [[local shared object]]s.<ref>{{Cite web|url=http://www.h-online.com/security/news/item/Adobe-Flash-10-1-supports-private-browsing-994737.html|title=Adobe Flash 10.1 supports "private browsing"|website=The H|access-date=2019-08-14}}</ref><ref>{{Cite web|url=https://www.eweek.com/security/adobe-flash-player-private-browsing-may-force-change-in-fraud-fight|title=Adobe Flash Player Private Browsing May Force Change in Fraud Fight |website=[[eWeek]]|date=12 April 2010 |access-date=2019-08-14}}</ref>

==Uses== Private browsing modes are commonly used for various purposes, such as concealing visits to sensitive websites (like adult-oriented content) from the browsing history, conducting unbiased web searches [[Personalized search|unaffected]] by [[Filter bubble|previous browsing habits or recorded interests]], offering a "clean" temporary session for guest users (for instance, on [[public computer]]s),<ref>{{Cite web |last=Paul |first=Ian |date=2014-03-11 |title=Three practical reasons to use your browser's private mode |url=https://www.pcworld.com/article/2106766/three-practical-reasons-to-use-your-browsers-private-mode.html |access-date=2019-08-14 |website=PCWorld |language=en}}</ref> and managing multiple accounts on websites simultaneously. Private browsing can also be used to circumvent [[Paywall|metered paywalls]] on some websites.<ref name=":1" />

In a survey conducted by [[DuckDuckGo]], 48% of participants chose not to respond, prompting lead researcher [[Elie Bursztein]] to observe, "Surveys are clearly not the best approach to understand why people use private browsing mode due to the embarrassment factor." Additionally, 18% of respondents indicated that their main use of private browsing modes was for [[online shopping]].<ref name=":2">{{Cite web|url=https://www.elie.net/blog/privacy/understanding-how-people-use-private-browsing|title=Understanding how people use private browsing|last=Bursztein|first=Elie|author-link1=Elie Bursztein|language=en|access-date=2019-08-14}}</ref><ref>{{Cite web|url=https://www.zdnet.com/article/private-browsing-tools-still-leave-data-trail/|title=Private browsing tools still leave data trail|last=Espiner|first=Tom|website=ZDNet|language=en|access-date=2019-08-14}}</ref><ref>{{Cite web|url=https://www.zdnet.com/pictures/private-browsing-good-reasons-to-use-incognito-privacy-porn-mode/|archive-url=https://web.archive.org/web/20180622111538/https://www.zdnet.com/pictures/private-browsing-good-reasons-to-use-incognito-privacy-porn-mode/|url-status=dead|archive-date=22 June 2018|title=Private browsing: 16 good reasons to use incognito mode|website=ZDNet|language=en|access-date=2019-08-14}}</ref>

A study by the [[Mozilla Foundation]] found that most sessions lasted only about 10 minutes. However, there were periods of increased activation, usually from 11 a.m. to 2 p.m., at 5 p.m., between 9 p.m. and 10 p.m., and a minor peak occurred about an hour or two after midnight.<ref>{{cite web|last=Ulmer|first=Hamilton|title=Understanding Private Browsing|url=http://blog.mozilla.com/metrics/2010/08/23/understanding-private-browsing/|work=Blog of Metrics|publisher=[[Mozilla Foundation]]|access-date=24 August 2010|date=23 August 2010}}</ref>

==Support in popular browsers== Private browsing is known by different names in different browsers.<ref name=PrivacyMode>{{cite news|url=https://www.digitalcitizen.life/how-browse-web-incognito-all-big-browsers|title=How to go incognito in all web browsers: Chrome, Firefox, Opera, Edge, and Internet Explorer|date=9 November 2018|work=Digital Citizen|last=Parchisanu|first=Daniel|access-date=9 January 2019}}</ref> {|class="wikitable sortable" "width: auto;" !rowspan=2|Date !rowspan=2|Introduced with/included in !rowspan=2|Synonym !colspan=2|Activation |- ! !macOS |- |{{Start date|df=yes|2005|04|29}} |[[Safari (web browser)|Safari]] 2.0 |Private Browsing | ||{{#invoke:key|press|Cmd|Shift|N}} |- |{{Start date|df=yes|2008|12|11}} |[[Google Chrome]] |[[Google Chrome#Incognito mode|Incognito]]<ref>{{Cite web |last=Porciello |first=Loris |date=2024-05-23 |title=Non farti spiare quando navighi, la funzione Google che ti permette di salvare la tua privacy |url=https://www.osservatorioiraq.it/non-farti-spiare-quando-navighi-la-funzione-google-che-ti-permette-di-salvare-la-tua-privacy/ |access-date=2024-08-31 |website=OsservatorioIraq |language=it-IT}}</ref> |{{#invoke:key|press|Ctrl|Shift|N}}|| {{#invoke:key|press|Cmd|Shift|N}} |- |{{Start date|df=yes|2009|03|19}}<ref>{{Cite press release|url=http://news.prnewswire.com/ViewContent.aspx?ACCT=109&STORY=/www/story/03-19-2009/0004991142|publisher=[[Microsoft]]|title=Microsoft Announces Availability of Internet Explorer 8|access-date=16 December 2011|date=19 March 2009|url-status=dead |archive-url=https://web.archive.org/web/20090322090328/http://news.prnewswire.com/ViewContent.aspx?ACCT=109&STORY=%2Fwww%2Fstory%2F03-19-2009%2F0004991142|archive-date=22 March 2009}}</ref> |[[Internet Explorer 8]] |[[Internet Explorer 8#InPrivate|InPrivate Browsing]] |{{#invoke:key|press|Ctrl|Shift|P}}|| {{#invoke:key|press|Cmd|Shift|P}} |- |{{Start date|df=yes|2009|06|30}} |[[Mozilla Firefox 3.5]]<ref>{{cite web|url=https://mxr.mozilla.org/mozilla1.9.1/source/browser/locales/en-US/chrome/browser/aboutPrivateBrowsing.dtd#1|title=Mozilla Cross-Reference mozilla1.9.1|publisher=[[Mozilla Foundation]]|access-date=2009-05-26}}</ref> |Private Browsing |{{#invoke:key|press|Ctrl|Shift|P}}|| {{#invoke:key|press|Cmd|Shift|P}} |- |{{Start date|df=yes|2010|03|02}} |[[Opera 10#10.50|Opera 10.50]]<ref>{{cite web|url=http://labs.opera.com/news/2009/12/22/|title=Opera 10.5 pre-alpha for Labs|publisher=[[Opera Software]]|access-date=2009-12-22|first=Roberto|last=Mateu|url-status=dead |archive-url=https://web.archive.org/web/20110824224909/http://labs.opera.com/news/2009/12/22/|archive-date=2011-08-24}}</ref> |Private Tab / Private Window |{{#invoke:key|press|Ctrl|Shift|N}}||{{#invoke:key|press|Cmd|Shift|N}} |- |{{Start date|df=yes|2014|11|18}} |[[Amazon Silk]]<ref>{{cite web|url=https://amazonsilk.wordpress.com/2014/11/18/private-browsing-for-amazon-silk/|title=Private Browsing for Amazon Silk|publisher=[[Amazon Inc.]]|access-date=2014-11-18|url-status=dead |archive-url=https://web.archive.org/web/20141222053804/https://amazonsilk.wordpress.com/2014/11/18/private-browsing-for-amazon-silk/|archive-date=2014-12-22}}</ref> |Private Browsing |colspan=2|Swipe from the left edge of the screen,<br>then tap Settings and select Enter Private Browsing |- |{{Start date|df=yes|2015|07|29}} |[[Microsoft Edge]] |InPrivate Browsing |{{#invoke:key|press|Ctrl|Shift|N}}||{{#invoke:key|press|Cmd|Shift|P}} |- |{{Start date|df=yes|2019|11|13}} |[[Brave (web browser)|Brave]] |Private Browsing |{{#invoke:key|press|Ctrl|Shift|N}}||{{#invoke:key|press|Cmd|Shift|N}} |}

==Security== It is a [[common misconception]] that private browsing modes can protect users from being [[Web tracking|tracked]] by other websites or their [[Internet service provider]] (ISP).<ref name="fastco-wont"/> Such entities can still use information such as [[IP address]]es and [[user accounts]] to uniquely identify users.<ref name="fastco-wont">{{Cite web|url=https://www.fastcompany.com/90311396/incognito-mode-wont-keep-you-private-try-browser-compartmentalization|title=Incognito mode won't keep your browsing private. Do this instead|last=Grothaus|first=Michael|date=2019-04-12|website=Fast Company|language=en-US|access-date=2019-08-14}}</ref><ref>{{cite web |url=https://www.privacyflake.com/2018/08/incognito-mode-browsing-myths.html |title=Incognito mode while browsing - Myths Busted - Privacyflake |website=www.privacyflake.com |url-status=dead |archive-url=https://web.archive.org/web/20190905051703/https://www.privacyflake.com/2018/08/incognito-mode-browsing-myths.html |archive-date=2019-09-05}}</ref> Private browsers on [[iOS]], not created by [[Apple Inc.|Apple]], must adhere to specific standards and regulations to be available on its platform for [[iPhone]] and [[iPad]]. Specifically, these browsers are required to employ the [[WebKit]] framework for rendering web pages. Consequently, third-party browsers cannot use their own rendering engines and must depend on Apple's framework instead. This constraint impacts the range of privacy features that these browsers can provide.<ref>{{Cite web |date=2023-03-02 |title=8 Best Private Browsers for iOS. Our picks for iPhone & iPad users [2024] {{!}} Incogni |url=https://blog.incogni.com/best-private-browsers-for-ios/ |access-date=2024-03-14 |website=blog.incogni.com |language=en-US}}</ref> This is one of the reasons why some browsers have partly addressed this shortcoming by offering additional privacy features that can be automatically enabled when using private browsing mode, such as Firefox's "Tracking Protection" feature to control use of web trackers (which has since been rolled into a larger "content blocking" function extended outside of private browsing mode), and [[Opera (web browser)|Opera]] offering an in-house [[Virtual private network|VPN]] service embedded within the browser.<ref>{{Cite web|url=https://www.zdnet.com/article/firefox-63-released-with-always-on-tracking-protection/|title=Firefox 63 released with 'always-on' tracking protection|last=Cimpanu|first=Catalin|website=ZDNet|language=en|access-date=2019-08-14}}</ref><ref name=":2" />

[[Brazil]]ian researchers published the results of a project in which they applied [[Computer forensics|forensic]] techniques (namely the Foremost data carving tool and Strings program) to extract information about the user's browsing activities on Internet Explorer and Firefox browsers with their private mode enabled. They were able to collect enough data to identify pages visited and even to partially reconstruct them.<ref>R. Ruiz, F. P. Amatte, K. J. B. Park, [https://www.researchgate.net/publication/258491690_Making_the_In_Private_Navigation_as_Public_%28Tornando_Pblica_a_Navegao_In_Private%29_Portuguese Tornando Pública a Navegação "In Private"]. Proceedings of the Seventh International Conference on Forensic Computer Science – ICoFCS 2012, Available online Sep 2012.</ref> This research was later extended to include the Chrome and Safari browsers. The gathered data proved that the browsers' private mode implementations cannot fully hide users' browsing activities and that browsers in private mode leave traces of activities in caching structures and files related to the [[paging]] process of the [[operating system]].<ref>R. Ruiz, F. P. Amatte, K. J. B. Park, [https://www.researchgate.net/publication/271497300_Opening_the__Private_Browsing__Data__Acquiring_Evidence_of_Browsing_Activities Opening the "Private Browsing" Data – Acquiring Evidence of Browsing Activities]. Proceedings of the International Conference on Information Security and Cyber Forensics (InfoSec2014), Available online Oct 2014.</ref>

Another independent security analysis, performed by a group of researchers at [[Newcastle University]], reported a range of potential security vulnerabilities in the implementation of the private modes across Chrome, Firefox, Internet Explorer, and Safari, including that:<ref>{{Cite journal |doi = 10.1016/j.jisa.2014.02.002|title = On the privacy of private browsing – A forensic approach|journal = Journal of Information Security and Applications|volume = 19|pages = 88–100|year = 2014|last1 = Satvat|first1 = Kiavash|last2 = Forshaw|first2 = Matthew|last3 = Hao|first3 = Feng|last4 = Toreini|first4 = Ehsan|url = https://eprint.ncl.ac.uk/fulltext.aspx?url=197264/D8ACC693-D092-41D2-8682-1521007F31A6.pdf&pub_id=197264}}</ref> * [[Browser extension]]s could still record history if they were active in private mode. Although Chrome and Firefox have since required extensions to be enabled on an opt-in basis for their private browsing modes,<ref>{{Cite web|url=https://www.computerworld.com/article/3356840/how-to-go-incognito-in-chrome-firefox-safari-and-edge.html|title=How to go incognito in Chrome, Firefox, Safari and Edge|last=Keizer|first=Gregg|date=2019-03-08|website=Computerworld|language=en|access-date=2019-08-14}}</ref> an installed extension in the normal mode could learn the user's activities in the private mode by measuring the usage of shared computing resources. * Data erasure by the browser alone is found to be insufficient. For example, the records of visited websites during the private session can be retained in memory for a long time even after the private session is closed. In addition, the visited website records are usually kept by the operating system in the local [[Domain Name System|DNS]] cache.<ref>{{cite news |last1=Verger |first1=Rob |title=Your private browsing isn't as incognito as you want it to be |url=https://www.popsci.com/private-browsing/ |access-date=24 September 2020 |date=26 February 2018}}</ref> Furthermore, the modified timestamps of certain profile files saved on the disk may reveal if the private mode was previously turned on and when it was turned on. * [[Software bug]]s present in some browsers were found to seriously degrade the security of the private mode. For example, in some earlier versions of Safari, the browser retained private browsing history records if the browser program was not closed normally (e.g., as a result of a crash), or if the user acted to add a [[Bookmark (World Wide Web)|bookmark]] within the private mode. * Depending on whether the session is in the private or the normal mode, web browsers typically exhibit different [[user interface]]s and traffic characteristics. This allows a remote website to tell if the user is currently in the private mode: for example, by checking the color of the hyperlinks or measuring the time of writing cookies.

Bugs and security vulnerabilities in extensions themselves may also leak personally identifiable data from private mode.<ref>B. Zhao, P. Liu, [http://s2.ist.psu.edu/paper/DSN_CameraReady-Bin-Zhao-PBM-18March2015.pdf Private Browsing Mode Not Really That Private: Dealing with Privacy Breaches Caused by Browser Extensions]. In Proceedings of the 45th Annual IEEE/IFIP International Conference on Dependable Systems and Networks (DSN 2015), Rio de Janeiro, Brazil, Available online June 2015.</ref>

Implementations of the [[HTML5]] FileSystem API can be used to detect users in private mode. In Google Chrome, the FileSystem API was not available in Incognito mode prior to version 76. To [[Digital rights management|prevent circumvention]] of [[paywall]] policies and evasion of [[web tracking]] scripts used to monetize traffic, a number of websites — including ''[[The New York Times]]'' — have used such behavior to block access to users in private browsing mode, and requiring them to subscribe or log in. Chrome 76 allows the FileSystem API to be used in Incognito mode; explaining the change, Google argued that the ability to detect the use of Incognito mode infringes on users' privacy. However, it was later discovered that the disk space quotas for the API differed between normal and Incognito modes, providing another means by which to detect Incognito users.<ref>{{Cite web|url=https://www.zdnet.com/article/chromes-more-private-incognito-mode-websites-can-still-detect-youre-using-it/|title=Chrome's 'more private' Incognito mode: Websites can still detect you're using it|last=Tung|first=Liam|website=ZDNet|language=en|access-date=2019-08-14}}</ref><ref name=":1">{{Cite web|url=https://slate.com/technology/2019/07/google-chrome-update-incognito-mode-paywall-workaround.html|title=Google's Chrome Update Just Unlocked Lots of Newspapers' Metered Paywalls|last=Brownlee|first=Chip|date=2019-07-31|website=Slate Magazine|language=en|access-date=2019-08-14}}</ref><ref>{{Cite web|url=https://www.zdnet.com/article/google-to-clamp-down-on-incognito-mode-detection/|title=Google to clamp down on Incognito Mode detection|last=Duckett|first=Chris|website=ZDNet|language=en|access-date=2019-08-14}}</ref> Despite statements otherwise by Google, this has not yet been patched. Scripts have also been developed to detect private browsing mode on other browsers, such as Firefox.<ref>{{Cite web|last=Cimpanu|first=Catalin|title=Incognito mode detection still works in Chrome despite promise to fix|url=https://www.zdnet.com/article/incognito-mode-detection-still-works-in-chrome-despite-promise-to-fix/|access-date=2020-06-25|website=ZDNet|language=en}}</ref>

=== Associated lawsuit === In December 2023, Google settled a $5 billion consumer privacy lawsuit that alleged that its practices allowed it to track users in private browsing mode in various browsers.<ref>{{Cite web |last1=Stempel |first1=Jonathan |title=Google settles $5 billion consumer privacy lawsuit |work=Reuters |date=29 December 2023 |url=https://www.reuters.com/legal/google-settles-5-billion-consumer-privacy-lawsuit-2023-12-28/}}</ref>

== See also == * [[Dark web]] * [[Internet privacy]] * [[Web browser]]

== References == {{Reflist}}

{{DEFAULTSORT:Privacy Mode}} [[Category:Web browsers]] [[Category:Internet privacy]] [[Category:2005 introductions]]