Private browsing

Privacy mode or "private browsing" or "incognito mode" is a privacy feature in some web browsers to disable browsing history and the web cache. This allows a person to browse the Web without storing local data that could be retrieved at a later date. Privacy mode will also disable the storage of data in cookies and Flash cookies. This privacy protection is only on the local computing device as it is still possible to identify frequented websites by associating the IP address at the web server.

The earliest reference to privacy mode was in May 2005 and used to discuss the privacy features in the Safari 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. However, privacy modes operate as shields because browsers typically do not remove all data from the cache after the session. Plugins, like Silverlight, 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 web feed with sites approved for use with InPrivate browsing.

The common web browser plugin Adobe Flash Player began supporting privacy mode in Chrome, Firefox, Internet Explorer, and Safari with the release of version 10.1 in June 2010.

Privacy mode has multiple uses, including:

The Mozilla Foundation performed 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 11 a.m. to 2 p.m., 5 p.m., between 9 p.m. and 10 p.m., and a minor peak about an hour or two after midnight.

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