Mozilla Firefox the second-most widely used 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 (URI) and may be a web page image video or other piece of content.1 Hyperlinks present in resources enable users to easily navigate their browsers to related resources.

Although browsers are primarily intended to access the World Wide Web they can also be used to access information provided by web servers in private networks or files in file systems.

The major web browsers are Windows Internet Explorer Mozilla Firefox Google Chrome Apple Safari and Opera. Contents 1 History 2 Function 3 Features 3.1 User interface 3.2 Privacy and security 3.3 Standards support 4 See also 5 References 6 External links History Main article: History of the web browser WorldWideWeb for NeXT released in 1991 was the first web browser.2

The history of the web browser dates back to the late 1980s when a variety of technologies laid the foundation for the first web browser WorldWideWeb by Tim Berners-Lee in 1991. That browser brought together a variety of existing and new software and hardware technologies.

The introduction of the NCSA Mosaic web browser in 1993 one of the first graphical web browsers led to an explosion in web use. Marc Andreessen the leader of the Mosaic team at NCSA soon started his own company named Netscape and released the Mosaic-influenced Netscape Navigator in 1994 which quickly became the world's most popular browser accounting for 90% of all web use at its peak (see usage share of web browsers).

Microsoft responded with its browser Internet Explorer in 1995 (also heavily influenced by Mosaic) initiating the industry's first browser war. By bundling Internet Explorer with Windows Microsoft was able to leverage its dominance in the operating system market to take over the web browser market; Internet Explorer usage share peaked at over 95% by 2002.3

Opera debuted in 1996; although it has never achieved widespread use having less than 1% browser usage share as of February 2009 according to Net Applications4 having grown to 2.14 in April 2011 its Opera-mini version has an additive share in April 2011 amounting to 1.11 % of overall browser use but focused on the fast-growing mobile phone web browser market being preinstalled on over 40 million phones. It is also available on several other embedded systems including Nintendo's Wii video game console.

In 1998 Netscape launched what was to become the Mozilla Foundation in an attempt to produce a competitive browser using the open source software model. That browser would eventually evolve into Firefox which developed a respectable following while still in the beta stage of development; shortly after the release of Firefox 1.0 in late 2004 Firefox (all versions) accounted for 7.4% of browser use.3 As of April 2011 Firefox has a 21.63% usage share.4

Apple's Safari had its first beta release in January 2003; as of April 2011 it has a dominant share of Apple-based web browsing accounting for just over 7.15% of the entire browser market.4 The most recent major entrant to the browser market is Google's Chrome first released in September 2008. As of April 2011 it has a 11.94% usage share.4 Function The primary purpose of a web browser is to bring information resources to the user. This process begins when the user inputs a Uniform Resource Identifier (URI) for example http://en.wikipedia.org/ into the browser. The prefix of the URI determines how the URI will be interpreted. The most commonly used kind of URI starts with http: and identifies a resource to be retrieved over the Hypertext Transfer Protocol (HTTP). Many browsers also support a variety of other prefixes such as https: for HTTPS ftp: for the File Transfer Protocol and file: for local files. Prefixes that the web browser cannot directly handle are often handed off to another application entirely. For example mailto: URIs are usually passed to the user's default e-mail application and news: URIs are passed to the user's default newsgroup reader. In the case of http https file and others once the resource has been retrieved the web browser will display it. HTML is passed to the browser's layout engine to be transformed from markup to an interactive document. Aside from HTML web browsers can generally display any kind of content that can be part of a web page. Most browsers can display images audio video and XML files and often have plug-ins to support Flash applications and Java applets. Upon encountering a file of an unsupported type or a file that is set up to be downloaded rather than displayed the browser prompts the user to save the file to disk. Information resources may contain hyperlinks to other information resources. Each link contains the URI of a resource to go to. When a link is clicked the browser navigates to the resource indicated by the link's target URI and the process of bringing content to the user begins again. Features For more details on this topic see Comparison of web browsers. Available web browsers range in features from minimal text-based user interfaces with bare-bones support for HTML to rich user interfaces supporting a wide variety of file formats and protocols. Browsers which include additional components to support e-mail Usenet news and Internet Relay Chat (IRC) are sometimes referred to as "Internet suites" rather than merely "web browsers".567 All major web browsers allow the user to open multiple information resources at the same time either in different browser windows or in different tabs of the same window. Major browsers also include pop-up blockers to prevent unwanted windows from "popping up" without the user's consent.891011 Most web browsers can display a list of web pages that the user has bookmarked so that the user can quickly return to them. Bookmarks are also called "Favorites" in Internet Explorer. In addition all major web browsers have some form of built-in web feed aggregator. In Mozilla Firefox web feeds are formatted as "live bookmarks" and behave like a folder of bookmarks corresponding to recent entries in the feed.12 In Opera a more traditional feed reader is included which stores and displays the contents of the feed.13 Furthermore most browsers can be extended via plug-ins downloadable components that provide additional features. User interface Most major web browsers have these user interface elements in common:14 Back and forward buttons to go back to the previous resource and forward again. A refresh or reload button to reload the current resource. A stop button to cancel loading the resource. In some browsers the stop button is often merged with the reload button. A home button to return to the user's home page An address bar to input the Uniform Resource Identifier (URI) of the desired resource and display it. A search bar to input terms into a search engine A status bar to display progress in loading the resource and also the URI of links when the cursor hovers over them and page zooming capability. Major browsers also possess incremental find features to search within a web page. Privacy and security Most browsers support HTTP Secure and offer quick and easy ways to delete the web cache cookies and browsing history. For a comparison of the current security vulnerabilities of browsers see comparison of web browsers. Standards support Early web browsers supported only a very simple version of HTML. The rapid development of proprietary web browsers led to the development of non-standard dialects of HTML leading to problems with interoperability. Modern web browsers support a combination of standards-based and de facto HTML and XHTML which should be rendered in the same way by all browsers. See also Browser wars Comparison of web browsers Geobrowsing Internet suite Layout engine List of web browsers Mobile browser Timeline of web browsers Usage share of web browsers References Jacobs Ian; Walsh Norman (15 December 2004). "URI/Resource Relationships". Architecture of the World Wide Web Volume One. World Wide Web Consortium. http://www.w3.org/TR/webarch/#id-resources. Retrieved 30 June 2009.  Stewart William. "Web Browser History". http://www.livinginternet.com/w/wibrowse.htm. Retrieved 5 May 2009.  a b http://www.searchenginejournal.com/mozilla-firefox-internet-browser-market-share-gains-to-74/1082/ a b c d http://marketshare.hitslink.com/browser-market-share.aspxqprid0 "The SeaMonkey Project". Mozilla Foundation. 7 November 2008. http://www.seamonkey-project.org/. Retrieved 30 June 2009.  "Cyberdog: Welcome to the 'doghouse!". 5 July 2009. http://www.cyberdog.org/. Retrieved 30 June 2009.  Teelucksingh Dev Anand. "Interesting DOS programs". Opus Networkx. http://www.opus.co.tt/dave/internet.htm. Retrieved 30 June 2009.  Andersen Starr; Abella Vincent (15 September 2004). "Part 5: Enhanced Browsing Security". Changes to Functionality in Microsoft Windows XP Service Pack 2. Microsoft. http://technet.microsoft.com/en-us/library/bb457150.aspx#EEAA. Retrieved 30 June 2009.  "Pop-up blocker". Mozilla Foundation. http://support.mozilla.com/en-US/kb/Pop-up+blocker. Retrieved 30 June 2009.  "Safari: Using The Pop-Up Blocker". Mac Tips and Tricks. WeHostMacs. 2004. http://www.mactipsandtricks.com/tips/display.lassomactip137. Retrieved 30 June 2009.  "Simple settings". Opera Tutorials. Opera Software. http://www.opera.com/browser/tutorials/settings/#tabs. Retrieved 30 June 2009.  Bokma John. "Mozilla Firefox: RSS and Live Bookmarks". http://johnbokma.com/firefox/rss-and-live-bookmarks.html. Retrieved 30 June 2009.  "RSS newsfeeds in Opera Mail". Opera Software. http://www.opera.com/mail/rss/. Retrieved 30 June 2009.  "About Browsers and their Features". SpiritWorks Software Development. http://www.about-the-web.com/shtml/browsers.shtml. 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