A web browser (commonly referred to as a browser) is a software application for accessing information on the World Wide Web. Each individual web page, image, and video is identified by a distinct URL, enabling browsers to retrieve and display them on the user's device.
Note that a web browser is not the same thing as a search engine, though the two are often confused. For a user, a search engine is just a website, such as google.com, that stores searchable data about other websites. But in order to connect to and display websites on their device, a user needs to have a web browser installed.
The first web browser, called WorldWideWeb, was invented in 1990 by Sir Tim Berners-Lee. He then recruited Nicola Pellow to write the Line Mode Browser, which displayed web pages on dumb terminals; it was released in 1991.
1993 was a landmark year with the release of Mosaic, credited as "the world's first popular browser". Its innovative graphical interface made the World Wide Web system easy to use and thus more accessible to the average person. This, in turn, sparked the Internet boom of the 1990s when the Web grew at a very rapid rate. Marc Andreessen, the leader of the Mosaic team, soon started his own company, Netscape, which released the Mosaic-influenced Netscape Navigator in 1994. Navigator quickly became the most popular browser.
Microsoft debuted Internet Explorer in 1995, leading to a browser war with Netscape. Microsoft was able to gain a dominant position for two reasons: it bundled Internet Explorer with its popular Windows operating system and did so as freeware with no restrictions on usage. Eventually the market share of Internet Explorer peaked at over 95% in 2002.
In 1998, desperate to remain competitive, Netscape launched what would become the Mozilla Foundation to create a new browser using the open source software model. This work evolved into Firefox, first released by Mozilla in 2004. Firefox reached a 28% market share in 2011.
The last major entrant to the browser market was Google. Its Chrome browser, which debuted in 2008, has been a huge success. It steadily took market share from Internet Explorer and became the most popular browser in 2012. It has remained dominant ever since.
The primary purpose of a web browser is to bring information resources to the user ("retrieval" or "fetching"), allowing them to view the information ("display", "rendering"), and then access other information ("navigation", "following links").
This process begins when the user inputs a Uniform Resource Locator (URL), for example http://en.wikipedia.org/, into the browser. The prefix of the URL, the Uniform Resource Identifier or URI, determines how the URL 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 and associated content (image files, formatting information such as CSS, etc.) is passed to the browser's layout engine to be transformed from markup to an interactive document, a process known as "rendering". 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.
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".
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.
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 Firefox, web feeds are formatted as "live bookmarks" and behave like a folder of bookmarks corresponding to recent entries in the feed. In Opera, a more traditional feed reader is included which stores and displays the contents of the feed.
Furthermore, most browsers can be extended via plug-ins, downloadable components that provide additional features.
Most major web browsers have these user interface elements in common:
- Back and forward buttons to go back to the previous resource and forward respectively.
- 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 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 web search engine. In some browsers, the search bar is merged with the address bar.
- 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.
- The viewport, the visible area of the webpage within the browser window.
- The ability to view the HTML source for a page.
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 personally identifiable information such as the web cache, download history, form and search history, cookies, and browsing history. For a comparison of the current security vulnerabilities of browsers, see comparison of web browsers.
A browser extension is a computer program that extends the functionality of a web browser. Every major web browser supports the development of browser extensions.
- "What is a Browser?". Google (on YouTube). 2009-04-30.
Less than 8% of people who were interviewed on this day knew what a browser was.
- "Difference Between Search Engine and Browser".
- "Tim Berners-Lee: WorldWideWeb, the first Web client". W3.org. Retrieved 2011-12-07.
- Gillies, James; Cailliau, R. (2000). How the Web was Born: The Story of the World Wide Web. Oxford University Press. p. 6. ISBN 0192862073.
- "Bloomberg Game Changers: Marc Andreessen". Bloomberg. 17 March 2011. Retrieved 2011-12-07.
- "Mozilla Firefox Internet Browser Market Share Gains to 7.4%". Search Engine Journal. 24 November 2004. Retrieved 2011-12-07.
- Stewart, William. "Web Browser History". Retrieved 5 May 2009.
- "Internet Explorer usage to plummet below 50 percent by mid-2012". 3 September 2011. Retrieved 4 September 2011.
- "StatCounter Global Stats – Browser, OS, Search Engine including Mobile Usage Share". Retrieved 2 May 2015.
- "Browser Information". DBF. Retrieved 2012-06-07.
- "Behind the scenes of modern web browsers". Tali Garsiel. Retrieved 12 October 2013.
- "The SeaMonkey Project". Mozilla Foundation. 7 November 2008. Retrieved 30 June 2009.
- "Cyberdog: Welcome to the 'doghouse!". 5 July 2009. Retrieved 30 June 2009.
- Teelucksingh, Dev Anand. "Interesting DOS programs". Opus Networkx. 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. Retrieved 30 June 2009.
- "Pop-up blocker". Mozilla Foundation. Retrieved 30 June 2009.
- "Safari: Using The Pop-Up Blocker". Mac Tips and Tricks. WeHostMacs. 2004. Retrieved 30 June 2009.
- "Simple settings". Opera Tutorials. Opera Software. Retrieved 30 June 2009.
- Bokma, John. "Mozilla Firefox: RSS and Live Bookmarks". Retrieved 30 June 2009.
- "RSS newsfeeds in Opera Mail". Opera Software. Retrieved 30 June 2009.
- "About Browsers and their Features". SpiritWorks Software Development. Retrieved 5 May 2009.
- "Desktop Browser Market Share Worldwide". StatCounter.
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