Microsoft - 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 .
Internet Explorer was not widely used until the release of version 3, when Internet Explorer was integrated into Windows Explorer and other core parts of Windows. This integration, 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 being 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 Windows 2000, 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. 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 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 was in line with the "Luna" visual style of Windows XP.
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 . 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: Pre-Beta 2 version) was released on January 31, 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. It includes important bug fixes, enhancements to support the web standards, improvements in HTML 4.01/CSS 2, Tabbed Browsing, Tab preview and management, and web feeds reader.
Features
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 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. This issue was addressed in Internet Explorer 6.0 SV1, which provides an Add-on Manager for controlling ActiveX controls and Browser Helper Objects. Internet Explorer 7 provides a "No Add-Ons" version (Under Programs/Accessories/System Tools) to address this issue, as well.
Usability and accessibility
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 can be added to Internet Explorer 6 by installing Microsoft's MSN Search Toolbar, and is natively supported as of Internet Explorer 7.
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, 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.
Internet Explorer 6 Service Pack 2 provides 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 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. 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.
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", 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.