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. An embedded OEM version called Internet Explorer for Windows CE (IE CE) is also available for WinCE based platforms and is currently based on IE6. Another Windows CE/ Windows Mobile browser known as Pocket Internet Explorer is from a different codebase and should not be confused with desktop versions of the browser.

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.

History

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

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.

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).

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.

Internet Explorer History

In the early 90s—the dawn of history as far as the World Wide Web is concerned—relatively few users were communicating across this global network. They used an assortment of shareware and other software for Microsoft Windows® operating system.
In 1995, Microsoft hosted an Internet Strategy Day and announced its commitment to adding Internet capabilities to all its products. In fulfillment of that announcement, Microsoft Internet Explorer arrived as both a graphical Web browser and the name for a set of technologies.
1995: Internet Explorer 1.0
In July 1995, Microsoft released the Windows 95 operating system, which included built-in support for dial-up networking and TCP/IP (Transmission Control Protocol/Internet Protocol), key technologies for connecting to the Internet. In response to the growing public interest in the Internet, Microsoft created an add-on to the operating system called Internet Explorer 1.0. When Windows 95 with Internet Explorer debuted, the Internet became much more accessible for many more people.
Internet Explorer technology originally shipped as the Internet Jumpstart Kit in Microsoft Plus! For Windows 95. Internet Explorer replaced the need for cumbersome, manual installation steps required by many of the existing shareware browsers.

1995: Internet Explorer 2.0
In November 1995, Microsoft released its first cross-platform browser, Internet Explorer 2.0, which supported both Macintosh and 32-bit Windows users.
With Internet Explorer 2.0 came a new set of fledgling Internet technologies that offered Web developers and designers the power to design secure, media-rich Web sites with tracking capabilities. Internet Explorer 2.0 technology introduced Secure Socket Layer (SSL) protocol as well as support for HTTP cookies, Virtual Reality Modeling Language (VRML), and Internet newsgroups.

1996: Internet Explorer 3.0
In August 1996, Microsoft released its completely rebuilt Internet Explorer technology, which included features that were revolutionary for the time. Designed for Windows 95, Internet Explorer 3.0 technology offered useful components that immediately appealed to users, including Internet Mail and News 1.0 and Windows Address Book. Later, Microsoft NetMeeting® and Windows Media Player were added. Now the Internet Explorer browser could display GIF and JPG files, play MIDI sound files, and play streaming audio files without the assistance of helper applications.
For Web developers, Internet Explorer 3.0 technology delivered a flexible programming model with a choice of scripting languages. Web designers also received more predictable results, thanks to Cascading Style Sheets (CSS). Moreoever, Internet Explorer 3.0 was designed to allow Web developers to extend it easily at a time when Internet standards were quickly evolving.

1997: Internet Explorer 4.0
Designed for Windows 95, Windows 98, and Windows NT®, Internet Explorer 4.0 technology was a significant move forward. For Web developers, the addition of Dynamic HTML (DHTML) heralded the next step in Web design. DHTML gave Web developers more control over content and style and created opportunities that previously had been possible only with software applications.
Suddenly Web pages became much more interactive—users could expand menus with a click or drag images and objects around. The Web started to look more like the applications and games that people were accustomed to and less like a static series of pages.
With Internet Explorer 4.0, Microsoft Outlook® Express 4.0 was also installed for the first time as an upgrade to Internet Mail and News. This built-in component improved the way users sent, received, and organized their e-mail and address book.

1998: Internet Explorer 5.0
With the September 1998 release of Internet Explorer 5.0 technology, developers gained the ability to design richer Web applications. DHTML capabilities were expanded, giving Web developers more flexibility and power to create interactive Web sites.
Now personalization became a key focus as Web applications based on DHTML emerged. Users encountered rich applications on the Web—for example, an expense report could automatically configure itself based on a user's personalized settings. With expanded programming capabilities such as these, Internet Explorer 5.0 technologies helped usher in a new era of e-commerce.

2001: Internet Explorer 6
Internet Explorer 6 technology was released with Windows XP in 2001 as a more private, reliable, and flexible technology than previous versions. Because privacy and security had become customer priorities, Microsoft implemented tools that support Platform for Privacy Preferences (P3P), a technology under development by the World Wide Web Consortium (W3C).
From the home user simply browsing content on the Web, to the IT administrator deploying and maintaining a rich set of Windows Internet technologies, to the Web developer creating rich Web content, Internet Explorer 6 technologies provide the freedom to experience the best of the Internet.

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 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.