Internet Explorer

Windows Internet Explorer

Main Wikipedia page in Windows Internet Explorer 7 on Windows Vista
Developer: Microsoft
Latest release: 7.0.6000.16386 / November 8 2006
OS: Microsoft Windows
Mac OS X (up to version 5.2.3)
Mac OS (up to version 5.1)
Solaris and HP-UX (up to version 5.0)
Use: Web browser
License: Freeware
Website: Windows Internet Explorer

Windows Internet Explorer (previously known as Microsoft Internet Explorer, abbreviated IE or MSIE) is a proprietary graphical web browser developed by Microsoft and included as part of the Microsoft Windows line of operating systems. It has been the most widely-used web browser since 1999.

Though released in 1995 as part of the initial OEM release of Windows 95, Internet Explorer was not included in the first retail, or shrink-wrap, release of Windows 95. The most recent release is version 7.0, which is available as a free update for Windows XP with Service Pack 2, and Windows Server 2003 with Service Pack 1, and is included with Windows Vista. Versions of Internet Explorer prior to 6.0 SP2 are also available as a separate download for versions of Windows prior to Windows XP. There is a version for Windows CE and Mobile called Pocket Internet Explorer.

After the first release for Windows 95, additional versions of Internet Explorer were developed for 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). Only the Windows version remains in active development; the Mac OS X version is no longer supported.




Internet Explorer was originally derived primarily from Spyglass Mosaic, an early commercial proprietary web browser. In 1996, Microsoft licensed Spyglass Mosaic from Spyglass for 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 used the NCSA Mosaic source code only sparingly.[1]

Internet Explorer was not widely used until the release of version 3, which was the first version developed without Spyglass sources (although still using Spyglass "technology", so the Spyglass licensing information remained in the program's documentation). Internet Explorer 4 was the first version integrated into Windows Explorer and other core parts of Windows. The integration with Windows, however, was subject to numerous criticisms (see United States v. Microsoft).

Internet Explorer 3 was the first major browser with CSS support. Released on August 13 1996, it introduced support for ActiveX controls, Java applets, inline multimedia, and the PICS system for content metadata. These improvements were significant, compared to its main competitor at the time, Netscape Navigator. Version 3 also came bundled with Internet Mail and News, NetMeeting, and an early version of the Windows Address Book, and was itself included with Windows 95 OSR 2. Version 3 proved to be the first popular version of Internet Explorer, which brought with it increased scrutiny. In the months following its release, a number of security and privacy vulnerabilities were found by researchers and hackers.

Version 4, released in September 1997, deepened the level of integration between the web browser and the underlying operating system. Installing version 4 on a Windows 95 or Windows NT 4 machine and choosing "Windows Desktop Update" would result in the traditional Windows Explorer being replaced by a version more akin to a web browser interface, as well as the Windows desktop itself being web-enabled via Active Desktop. This option was no longer available with the installers for later versions of Internet Explorer but was not removed from the system if already installed. Internet Explorer 4 introduced support for Group Policy, allowing companies to configure and lock down many aspects of the browser's configuration. Internet Mail and News was replaced with Outlook Express, and Microsoft Chat and an improved NetMeeting were also included. This version also was included with Windows 98.

Version 5, launched on March 18, 1999, and subsequently included with Windows 98 Second Edition and bundled with Office 2000, was another significant release that supported bi-directional text, ruby characters, XML, XSL and the ability to save web pages in MHTML format. (Windows 2000 included Internet Explorer 5.01 instead.) Version 5.5 followed in July 2000, improving its print preview capabilities, CSS and HTML standards support, and developer APIs; this version was bundled with Windows Me.

Version 6 was released on August 27, 2001, a few weeks before Windows XP. This version included DHTML enhancements, content restricted inline frames, and partial 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 was in line with the "Luna" visual style of Windows XP. In 2002, the Gopher protocol was disabled and support for it was dropped in Internet Explorer 7[2]

On February 15, 2005, Microsoft Chairman Bill Gates announced that the new version of its browser would be released at the RSA Conference 2005 in San Francisco.[3] The decision to update the browser occurred in the wake of declining market share due to the spread of the Mozilla Firefox browser. Microsoft also stated that Internet Explorer 7 is available only 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: Pre-Beta 2 version) was released on January 31, 2006. The final public version was released on October 18 2006. Version 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, including not being integrated as much with Windows [4] as previous versions, therefore increasing security. It includes important bug fixes, enhancements to support the web standards, improvements in HTML 4.01/CSS 2, Tabbed Browsing, Tab preview and management, multiple engine search box, and web feeds reader. It is also to be noted this is the first version of Internet Explorer not to be based upon Spyglass technologies.



Internet Explorer has been designed to view the broadest range of web pages and to provide certain features within the operating system, including Microsoft 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 functionality via Browser Helper Objects (BHO); and allows websites to offer rich content via ActiveX. As these objects can have the same privileges as the browser itself (in certain situations), there is a concern over security. Recent versions of Internet Explorer provide an Add-on Manager for controlling ActiveX controls and Browser Helper Objects and a "No Add-Ons" version (Under Programs/Accessories/System Tools).


Usability and accessibility

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 (although this feature requires a shell window to be opened in recent versions of the browser, rather than natively within the browser). VBA is not supported, but available via extension (iMacros).

Recent versions feature pop-up blocking and tabbed browsing. Tabbed browsing can also be added to older versions 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 the Windows Update service, as well as through Automatic Updates. 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.

Recent versions of Internet Explorer provide Download Monitoring and Install Monitoring allowing users the choice of whether or not to download and install executables, in two stages. This helps to prevent installation of malware. Executable files downloaded using Internet Explorer are marked by the operating system as being potentially unsafe, and will prompt the user to confirm they want to run the executable every time, until the user confirms the file is "safe".


Group Policy

Internet Explorer is fully configurable using Group Policy. Administrators of Windows Server domains can apply and enforce a variety of settings that affect the user interface (such as disabling menu items and individual configuration options), as well as underlying security features such as downloading of files, zone configuration, per-site settings, ActiveX control behavior, and others. Policy settings can be configured on a per-user and per-machine basis.


Standards support

Internet Explorer, using the Trident layout engine, 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. XML support brings with it support for XHTML, however Microsoft has buried this support since IE 5.0 making it difficult to access. Like other browsers it can consume XHTML when served as MIME type “text/html”. It can also consume XHTML as XML when served as MIME types “application/xml” and “text/xml”, however this requires a small XSLT measure[5] to re-enable the XHTML as XML support. It pretends to not comprehend XHTML when vended in the preferred type as “application/xhtml+xml” and instead treats it as an unfamiliar file type for download.

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 on screen (for printing Internet Explorer always uses standards mode). 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.


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.





Much criticism of Internet Explorer is related to concerns about security: Much of the spyware, adware, and computer viruses across the Internet are made possible by exploitable bugs and flaws in the security architecture of Internet Explorer, sometimes requiring nothing more than viewing of a malicious web page in order to install themselves. This is known as a "drive-by download": an attempt to trick the user into installing malicious software by misrepresenting the software's true purpose in the description section of an ActiveX security alert.

While Internet Explorer is not alone in having exploitable vulnerabilities, its ubiquity has resulted in many more affected computers when vulnerabilities are found. Microsoft has not responded as quickly as competitors in fixing security holes and making patches available.[6] Not only are there more security holes discovered in Internet Explorer, but these vulnerabilities tend to remain unpatched for a much longer time, in some cases giving malicious web site operators months to exploit them before Microsoft releases a patch. Several companies maintain databases of known security vulnerabilities that exist in Internet Explorer, for which no fixes have been published by Microsoft. As of November 27 2006, Secunia reports 3 unpatched vulnerabilities in Internet Explorer, of which the most severe vulnerability is rated "moderately critical".[7] In contrast, Mozilla Firefox, the main competitor to Internet Explorer, is reported to have 1 unpatched security vulnerability, rated "less critical."[8]

In May 2006, PC World rated Internet Explorer 6 the eighth worst tech product of all time.[9]


Standards support

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, because the browser often uses proprietary extensions to achieve similar functionality.

Internet Explorer supports, to some degree, a number of standardized technologies, but has numerous 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 inferiority in this area, frustrates developers who want to write standards-compliant, cross-browser code and the advanced functionality it provides, because they are often stuck coding pages around Internet Explorer's bugs, proprietary featureset, and missing standards support instead.

Web developers must work with the least advanced technology across all browsers they wish to support, and Internet Explorer is often criticized for being technically obsolete. These include supporting fewer CSS, HTML, and DOM features than Firefox or Opera and not having native XHTML support.[10] For another long-standing concrete example, see Internet Explorer's poor PNG transparency support, which remained unfixed until Internet Explorer 7.


Market adoption


Usage share

Further information: Usage share of web browsers
Usage share of Internet Explorer, 1996–2006
Usage share of Internet Explorer, 1996–2006

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 2.0 with Windows 95 OSR 1 in 1996, and especially after version 4.0's release, 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 small steady decline, due to the adoption of Mozilla Firefox, which statistics indicate is currently the most significant competition. Nevertheless, Internet Explorer remains the dominant web browser, with a global usage share of around 85% (based on statistics reference). Usage is higher in Asia and lower in Europe. For example, the share is around 94% in Japan,[11] and around 56% in Germany.[12]


Industry adoption

ActiveX is used by many public websites and web applications, including eBay. Similarly, Browser Helper Objects 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 content-centric applications like RealPlayer also use Internet Explorer's web browsing module for viewing web pages 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 have successfully separated several versions of Internet Explorer, making them standalone applications. These are referred to as "standalone" IEs and have included versions 3.0 to 5.5.

Microsoft has discontinued standalone installers for Internet Explorer to the general public. However, there are unofficial procedures for downloading the complete install package. Internet Explorer standalone hacks exploit a known workaround to DLL hell, which was introduced in Windows 2000, called DLL redirection.



While a major upgrade of Internet Explorer can be uninstalled in a traditional way if the user has saved the original application files for uninstallation, the matter of uninstalling the version of the browser that has shipped with an operating system remains a controversial one.

The idea of removing a stock install of 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.

The Australian computer scientist Shane Brooks demonstrated that Windows 98 could in fact run with Internet Explorer removed.[13] 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. However, both of these pieces of software work, in part, by installing obsolete versions of components (such as Windows Explorer) required by the operating system to function.

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. In some older versions of Windows and in Windows Fundamentals there is an option to install Internet Explorer.

Removing Internet Explorer does have a number of consequences. Some applications that depend on libraries installed by IE may fail to function, or have unexpected behaviors. Intuit's Quicken is a typical example, which depends heavily upon the HTML rendering components installed by the browser. The Windows help and support system will also not function due to the heavy reliance on HTML help files and components of IE. It is also not possible to run Microsoft's Windows Update with any other browser due to the service's implementation of an ActiveX control, which no other browser supports. Another possibility is to use AutoPatcher, an unofficial and unauthorised update manager, which does not require the use of a web browser at all.



  1. Eric Sink (2005-05-12). Memoirs From the Browser Wars. Retrieved on 2006-03-24.
    See also
  3. Gates Highlights Progress on Security, Outlines Next Steps for Continued Innovation, May 12 2005.
  4. Article regarding Internet Explorer 7's integration into windows, March 24 2006.
  5. see small XSLT measure Anne’s Weblog] for a sample of the minimal transformation required.
  6. Firefox Sports More Bugs, But IE Takes 9 Times Longer To Patch, TechWeb.
  7. Microsoft Internet Explorer 7.x, Secunia
  8. Mozilla Firefox 2.x, Secunia
  9. PCWorld (2005-05-26). The 25 Worst Tech Products of All Time. Retrieved on 2006-07-18.
  10. Web browser standards support summary. Web Devout.
  11. Firefox's Market Share Nears 7 Percent, WebSideStory
  12. Global usage share Mozilla Firefox has increased, OneStat
  13. U.S. v. Microsoft: Court's Findings of Fact. United States Department of Justice (2005-11-05). Retrieved on 2005-05-12..



See also


External links

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