Friday, February 10, 2006

Internet Explorer

Windows Internet Explorer logo  Internet Explorer
Internet Explorer 6 under Windows XP
Maintainer: Microsoft, Spyglass
Latest release: 6.0 SP 2 / August 6, 2004
Preview release: 7.0 Beta 2 Preview (build 5296) / January 31, 2006
OS: Windows
Genre: Web browser
License: Closed source
Website: Internet Explorer

Internet Explorer, abbreviated IE or MSIE, is a proprietary graphical web browser made by Microsoft and currently available as part of Microsoft Windows. Internet Explorer is the most widely used web browser today, although since 2004 it has been losing usage share to other browsers. As of October 2005, IE's usage share is about 85% (see the market adoption section).

Internet Explorer is an integrated component of all current versions of Microsoft Windows. Microsoft has shipped Internet Explorer as the default browser in all versions of Microsoft Windows since Windows 95 OSR1. The last major upgrade to Internet Explorer was included in Windows XP Service Pack 2, but is not available for older versions of Windows. The beta version of Internet Explorer 7 for Windows XP SP2 has been available since July 27, 2005.

Internet Explorer is available as a separate download for many older versions of Windows. In the past it was also developed for several other operating systems: Internet Explorer for Mac and Internet Explorer for UNIX (the latter for use through the X Window System on Solaris and HP-UX). All of these versions have ceased active development.

Internet Explorer is currently known as Microsoft Internet Explorer, but the name will change to Windows Internet Explorer with the release of Internet Explorer 7.




Internet Explorer 4.0 under Windows
Internet Explorer 4.0 under Windows
Main article: History of Internet Explorer

Internet Explorer is derived from Spyglass Mosaic, an early commercial web browser. In 1995, Spyglass Mosaic was licensed by Microsoft in an arrangement under which Spyglass would receive a quarterly fee plus a percentage of Microsoft's revenues for the software. Although bearing a name similar to NCSA Mosaic, which was the first widely used browser, Spyglass Mosaic was relatively unknown in its day and did not use any of the NCSA Mosaic source code [1].

Internet Explorer 3 was the first major browser with CSS support released in August, 1996 and it could handle the PICS system for content metadata. The improvements were significant, compared to its main competitor at the time, Netscape Navigator.

The browser was not widely used until version 4, which was released in October 1997 and was integrated with the Windows 98 operating system. This integration, however, was subject to numerous criticisms (see United States v. Microsoft). Version 5, released in September 1998, was another significant release that supported bi-directional text, ruby characters, XML and XSL.

Version 6 was released on August 27, 2001, a few weeks before Windows XP. This version included DHTML enhancements, content restricted inline frames, and better support of CSS level 1, DOM level 1 and SMIL 2.0. The MSXML engine was also updated to version 3.0. Other new features included a new version of the IEAK, Media bar, Windows Messenger integration, fault collection, automatic image resizing, P3P, and a new look-and-feel that is in line with the style of Windows XP.

On February 15, 2005, Microsoft Chairman Bill Gates announced that the new version of its browser will be released at the RSA Conference 2005 in San Francisco [2]. The decision to update the browser occurred in the wake of a decline in the use of Internet Explorer for the first time. Microsoft also stated that Internet Explorer 7 will only be available for Windows XP SP2 and later, including Windows Server 2003 SP1 and Windows Vista. The first beta version of the browser was released on July 27, 2005 for technical testing, and a first public preview version of Internet Explorer 7 (Beta 2 preview) was released on January 31, 2006. Verison 7 is intended to defend users from phishing as well as deceptive or malicious software, and also features full user control of ActiveX, and better security framework. It includes important bug fixes, enhancements to support the web standards, improvements in HTML 4.01/CSS 2, Tabbed Browsing, Tab preview/ management, and web feeds reader.


Main article: Features of Internet Explorer
The pop-up blocker included in Internet Explorer 6 SP 2
The pop-up blocker included in Internet Explorer 6 SP 2

Internet Explorer has been designed to view the broadest range of web pages and to provide certain features within the operating system, including Windows Update. During the heydays of the historic browser wars, Internet Explorer superseded Netscape by supporting many of the progressive features of the time.

Component architecture

The Component Object Model (COM) technology is used extensively in Internet Explorer. It allows third parties to add functionalities via Browser Helper Objects (BHO); and allows websites to offer rich content via ActiveX. As these objects have the same privileges as the browser itself (in certain situations), this raised concern over security. This issue was addressed in Internet Explorer 6.0 Service Pack 2, which provides an Add-on Manager for controlling ActiveX controls and Browser Helper Objects.

Usability and accessibility

Tabbed browsing in Internet Explorer 7 Beta 2 preview
Tabbed browsing in Internet Explorer 7 Beta 2 preview

Since it is tightly integrated with the operating system, Internet Explorer makes use of the accessibility framework provided in Windows. Internet Explorer is also a user interface for FTP, with operations similar to that of Windows Explorer.

The ability to block popup windows was introduced with Internet Explorer 6.0, Service Pack 2.

Tabbed browsing, while not natively supported, can be added to Internet Explorer 6 by installing Microsoft's MSN Search Toolbar.

Security framework

Internet Explorer uses a zone-based security framework, which means that sites are grouped based upon certain conditions. It allows the restriction of broad areas of functionality, and also allows specific functions to be restricted.

Patches and updates to the browser are released periodically and made available through Windows Update website. Although security patches continue to be released for a range of platforms, most recent feature additions and security improvements are released for Windows XP only. A report in April 2005 showed that only 24% of corporate PCs had upgraded to XP SP2.

Internet Explorer 6 Service Pack 2 provide Download Monitoring and Install Monitoring that user can choose to download, or not to download and, choose to install, or not to install Applications, Executables and Installations. This prevents installation of Spywares, Adwares, Viruses or Malwares.

Standards support

Internet Explorer almost fully supports HTML 4.01, CSS Level 1, XML 1.0 and DOM Level 1, with minor implementation gaps. It partially supports CSS Level 2 and DOM Level 2, with some implementation gaps and conformance issues. It supports XHTML 1.0 to the extent that HTML 4.01 compatibility guidelines are followed. Internet Explorer uses DOCTYPE sniffing to choose between "quirks mode" (renders similarly to older versions of MSIE) and standards mode (renders closer to W3C's specifications) for HTML and CSS rendering. It fully supports XSLT 1.0 or the December 1998 Working Draft of XSL, depending on the version of MSXML (a dynamic link library) available. It also provides its own dialect of ECMAScript called JScript.

Quick tabs in Internet Explorer 7 Beta 2 preview
Quick tabs in Internet Explorer 7 Beta 2 preview

Proprietary extensions

Internet Explorer has introduced an array of proprietary extensions to many of the standards, including HTML, CSS and the DOM. This has resulted in a number of web pages that can only be viewed properly using Internet Explorer. Many view this as an example of what is called "embrace, extend and extinguish" (EEE), a way to drive competitors out of business by forcing them to use proprietary technology that a company controls, resulting in vendor lock-in. Netscape Navigator up to version 4.7 was also responsible for massive proprietary extension of the core web standards, but was not criticized for it as much.

Version 7.0

For version 7.0 of Internet Explorer, set to ship with Windows Vista and as a separate download for Windows XP with Service Pack 2 and Windows Server 2003 Service Pack 1, large amounts of the architecture, including the security framework, have been completely overhauled. Partly as a result of these security enhancements, the browser will be a stand-alone application, rather than integrated with the Windows shell, and it will no longer be capable of acting as a file browser. The "beta 1" (build 5112) and "beta 2 preview" (build 5296) pre-releases both operate in this new stand-alone manner.

Two different versions of Internet Explorer 7.0, one for Windows XP with Service Pack 2, Windows 2003 Server with Service Pack 1 and x64 Editions and the other specific to Windows Vista, are going to be launched. The Windows Vista specific version will include all features of the other version. In addition it will run in a sandbox with even lower rights than a limited user account software. As such, it can write to only the Temporary Internet Files folder and can not install start-up programs or change any configuration of the Operating System. This should greatly increase the security of the system.

Feed reader integration in Internet Explorer 7 Beta 2 preview
Feed reader integration in Internet Explorer 7 Beta 2 preview

The browser supports Tabbed browsing in version 7.0. The beta 1 version includes tabbed browsing. It features QuickTabs in beta 2 version which is the thumbnail preview of opened tabs. With this new feature, user can find, open, close, and refresh opened tabs easily.

Web feeds support is built in version 7.0. The feed reader is fully integrated with the browser ,so that user can read Web Feeds(RSS/Atom) without an RSS reader. It also discovers web feeds automatically.

Internet Explorer supports a variety of graphics file formats, including GIF, JPEG and PNG. The long-awaited support for PNG alpha channel was introduced in 7.0 Beta 1.

ActiveX Opt-In blocks ActiveX Control unless it allowed to be installed. This feature improves security from unverificable and vulnerable controls. ActiveX controls can be chosen to be installed on Information Bar. User can turn on and off ActiveX Contol by using Add-on Manager.

On January 31st 2006, Microsoft released a public preview build (beta 2 preview) of Internet Explorer 7 for Windows XP Service Pack 2 (not for Windows Server 2003 SP 1) on their web site. It stated that more public preview builds of Internet Explorer 7 will be released in first half of 2006, and final version will be released in second half of 2006.[3]


Main article: Criticisms of Internet Explorer

Internet Explorer is subject to a relatively high volume of criticism. Much of this criticism is related to concerns about security: A notable portion of the widespread promulgation of spam, spyware, adware, and computer viruses across the Internet is known to be facilitated by exploitable bugs and flaws in the security architecture of Internet Explorer. Furthermore, a notable number of users and security experts have pointed out that Microsoft has not been sufficiently committed to fixing the browser's exploitable bugs in a timely manner, and has been ineffective in pushing those changes out to users. Several companies maintain databases of security vulnerabilities known to exist in Internet Explorer and for which no fixes have been published by Microsoft — as of June 2005, there were between 20 and 27 such vulnerabilities reported in Internet Explorer 6 for Windows XP SP2, and 146 in Internet Explorer 6 for Windows 2000 SP4.

Other criticisms, mostly coming from technically proficient users and developers of websites and browser-based software applications, concern Internet Explorer's support of open standards. Internet Explorer supports, to some degree, a number of standardized technologies, but has implementation gaps and conformance failures — some minor, some not — that have led to criticism from an increasing number of developers. The increase is attributable, in large part, to the fact that competing browsers that offer relatively thorough, standards-compliant implementations are becoming more widely used. Internet Explorer's ubiquity, in spite of its perceived inferiority in this area, frustrates developers who want to write standards-compliant, cross-browser code.

Market adoption

Usage share

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The adoption rate of Internet Explorer seems to be closely related to that of Microsoft Windows, as it is the default web browser that comes with Windows. Since the integration of Internet Explorer 3.0 with Windows 95 OSR 2 in late 1996, the adoption was greatly accelerated: from below 20% in 1996 to about 40% in 1998 and over 80% in 2000. This effect, however, has recently been dubbed the "Microsoft monoculture", by analogy to the problems associated with lack of biodiversity in an ecosystem. By 2002, Internet Explorer had almost completely superseded its main rival Netscape and dominated the market.

After having fought and won the browser wars of the late 1990s, Internet Explorer began to see its usage share shrink. Having attained a peak of about 96% in 2002, it has since been in a steady decline. Statistics indicate the current most significant competition comes from Gecko-based browsers, in particular Mozilla Firefox.

Nevertheless, Internet Explorer remains the dominant web browser, with a usage share of around 85% (based on statistics reference) in United States. around 93% in Japan, and around 70% in Germany.[4]

Industry adoption

ActiveX is used by many public websites and web applications, including eBay. Similarly, BHOs are also used by many search engine companies and third parties for creating add-ons that access their services, for example, search engine toolbars. Because of the use of COM, it is possible to include web-browsing functionality in third-party applications. Hence, there are a number of Internet Explorer shells, and a number of applications like RealPlayer (a media player) also use Internet Explorer's web browsing module for viewing the World Wide Web within the applications.

"Standalone" Internet Explorer

While it is not officially possible to keep multiple versions of Internet Explorer on the same machine, some hackers (Joe Maddalone, Ryan Parman, et al.) successfully separated several versions of Internet Explorer making them standalone applications. These were referred as "standalone" IEs and included versions 3.0 to 5.5 SP2.

Microsoft has discontinued standalone installers for Internet Explorer to the general public. However, a blogger/web developer/programmer named Liew Cheon Fong has posted a procedure for downloading the complete install package.


Main article: Removal of Internet Explorer

The idea of removing Internet Explorer from a Windows system was first proposed during the United States v. Microsoft case. Critics felt that users should have the right to uninstall Internet Explorer freely just like any other application software. One of Microsoft's arguments during the trial was that removing Internet Explorer from Windows may result in system instability.

An Australian computer scientist Shane Brooks demonstrated that Windows 98 could in fact run with IE files removed [5]. Brooks went on to develop software designed to customize Windows versions by removing "undesired components", which is known as 98lite. He later created XPLite to support NT based operating systems. Both of these pieces of software can remove IE after the installation of the operating system.

There are a few popular methods for removing IE from a copy of the Windows install disc so it never touches the user's hard drive. A method developed by Fred Vorck involves the manual removal of IE from installation discs. nLite, on the other hand, is an automated program that allows users to exclude IE and many other Windows components from installation as desired.

It is also not possible to run Microsoft's Windows Update with any other browser because of its use of DirectX, therefore removing Internet Explorer will cause this.


  1. ^  Memoirs From the Browser Wars, May 12, 2005.
  2. ^  Microsoft to abandon standalone IE, May 12, 2005.
  3. ^  Gates Highlights Progress on Security, Outlines Next Steps for Continued Innovation, May 12, 2005.
  4. ^  IE7 Platforms and Outlook Express, May 12, 2005.
  5. ^  U.S. v. Microsoft: Court's Findings of Fact, May 12, 2005.


See also

External links

Microsoft Corporation

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