Web browser
A web browser is a software package that enables a user to display and interact with documents hosted by web servers. It is the most commonly used kind of user agent. The largest networked collection of linked documents is known as the World Wide Web.
Protocols and standards
Web browsers communicate with web servers primarily using the HTTP protocol to fetch web pages identified by their URL (http:). HTTP allows web browsers to submit information to web servers as well as fetch web pages from them. The file format for a web page is usually HTML and is identified in the HTTP protocol using a MIME content type. Most browsers natively support a variety of formats in addition to HTML, such as the JPEG, PNG and GIF image formats, and can be extended to support more through the use of plugins. Many browsers also support a variety of other URL types and their corresponding protocols, such as ftp: for FTP, gopher: for Gopher, and https: for HTTPS (a SSL encrypted version of HTTP). The combination of HTTP content type and URL protocol specification allows web page designers to embed images, animations, video, sound, and streaming media into a web page, or to make them accessible through the web page.
Early web browsers supported only a very simple version of HTML. The rapid development of proprietary web browsers (see Browser Wars) led to the development of non-standard dialects of HTML, leading to problems with Web interoperability. Modern web browsers (Mozilla, Opera, and Safari) support standards-based HTML and XHTML (starting with HTML 4.01), which should display in the same way across all browsers. Internet Explorer does not fully support XHTML yet.
Some of the more popular browsers include additional components to support Usenet news and e-mail via the NNTP, SMTP, IMAP, and POP protocols.
Brief history
Tim Berners-Lee, who pioneered the use of hypertext for sharing information, created the first web browser, named WorldWideWeb, in 1990 and introduced it to colleagues at CERN in March 1991. Since then the development of web browsers has been inseparably intertwined with the development of the web itself.
The explosion in popularity of the web was triggered by NCSA Mosaic which was a graphical browser running originally on Unix but soon ported to the Apple Macintosh and Microsoft Windows platforms. Version 1.0 was released in September 1993. Marc Andreesen, who was the leader of the Mosaic team at NCSA, quit to form a company that would later be known as Netscape Communications Corporation.
Netscape released its flagship Navigator product in October 1994, and it took off the next year. Microsoft, which had so far missed the Internet wave, now entered the fray with its Internet Explorer product, hastily purchased from Spyglass Inc. This began the browser wars, the fight for the web browser market between the software giant Microsoft and the start-up company largely responsible for popularizing the World Wide Web, Netscape.
The wars put the web in the hands of millions of ordinary PC users, but showed how commercialization of the internet could ruin standards efforts. Both Microsoft and Netscape liberally incorporated proprietary extensions to HTML in their products, and tried to gain an edge by product differentiation. The wars ended in 1998 when it became clear that Netscape's declining marketshare trend was irreversible. This was in part due to Microsoft's integrating its browser with its operating system and bundling deals with OEMs; the company faced antitrust litigation on these charges.
Netscape responded by open sourcing its product, creating Mozilla. This did nothing to slow Netscape's declining marketshare. The company was purchased by America Online in late 1998. Mozilla has since evolved into a stable and powerful browser suite with a small but steady marketshare.
Opera, a speedy browser popular in handheld devices and in some European countries was released in 1996 and remains a niche player in the PC web browser market.
The Lynx browser remains popular in certain markets due to its entirely text-based nature.
While the Macintosh scene too has traditionally been dominated by Internet Explorer and Netscape, the future appears to belong to Apple's Safari which is based on the KHTML rendering engine of the open source Konqueror browser. Safari is the default browser on Mac OS X.
In 2003, Microsoft announced that Internet Explorer would no longer be made available as a separate product but would be part of the evolution of its Windows platform, and that no more releases for the Macintosh would be made.
Web and web browser features
Different browsers can be distinguished from each other by the features they support. Modern browsers and web pages tend to utilise many features and techniques that did not exist in the early days of the web. As noted earlier, with the browser wars there was a rapid and chaotic expansion of browser and World Wide Web feature sets. The following is a list of some of these elements and features:
- ActiveX
- Ad filtering
- Autocompletion of URLs and form data
- Bookmarks for keeping track of frequently accessed locations
- Cascading Style Sheets
- Cookies which enable a website to track a returning user
- Caching of web content
- CSS
- Digital certificates
- Download management
- DHTML
- Embedded images using established graphics file formats such as GIF, PNG, JPEG, SVG
- Flash
- Favicons
- Fonts, size, color
- Forms for submitting information
- Frames and IFrames
- History of recently visited pages
- HTTPS
- Image
- Integration with other desktop applications
- Offline browsing of cached content
- Java applet
- JavaScript for dynamic content
- Plug-ins
- Session management
- Tabbed browsing
- Tables
- XHTML and XML
Opera's "Small-Screen Rendering" is a special way to reformat webpages to fit inside the small screen width of a smartphone, thereby eliminating the need for horizontal scrolling.
Web browsers by market share
The following data, obtained by onestat.com, shows the proportion of users using each of the popular web browsers. The data, collected in May 2004, was obtained by looking at the user agent string of 2,000,000 users visiting a variety of different websites from 100 countries. [1]
(It should be noted that these statistics cannot be relied upon as a 100% accurate reflection of actual usage, because of something called "User agent spoofing". Sometimes, non-IE browsers are configured to "lie" about their identification, in order to access sites that would otherwise block them. Therefore, it is likely that Microsoft's Internet Explorer is slightly less dominant than these numbers show)
- Microsoft Internet Explorer-based browsers 93.9%
- Version 6 69.3% of total
- Version 5.5 12.9%
- Version 5 10.8%
- Version 4 0.6%
- Mozilla-based browers (including newer versions of Netscape) 2.1%
- Opera version 7 1.02%
- Safari 0.71%
See also
- List of web browsers
- Comparison of web browsers
- History of the Internet
- Browser exploit
- Browser-based software
- Accessibility
- Microbrowser