In an advisory on January 14, 2010, Microsoft said that attackers targeting Google and other U.S. companies used software that exploits a security hole, which had already been patched, in Internet Explorer. The vulnerability affected Internet Explorer 6, IE7, and IE8 on Windows 7, Vista, Windows XP, Server 2003, and Server 2008 R2, as well as IE 6 Service Pack 1 on Windows 2000 Service Pack 4.
The German government warned users against using Internet Explorer and recommended switching to an alternative web browser, due to the major security hole described above that was exploited in Internet Explorer. The Australian and French Government issued a similar warning a few days later. The first browser they recommended was Mozilla Firefox, followed by Google Chrome.
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.
A CNN article noted at the release of Internet Explorer 4: "Microsoft's Internet Explorer has made inroads and various estimates put its share of the browser market 30 to 35 percent from about 10 percent a year ago." By 2002, Internet Explorer had almost completely superseded its main rival Netscape and dominated the market with up to 95 percent market share.
After having fought and won the browser wars of the late 1990s, Internet Explorer gained almost total dominance of the browser market. Having attained a peak of about 95% during 2002 and 2003, its market share has since declined at a slow but steady pace. This is mainly 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 60% (though measurements vary). Usage is higher in Asia and lower in Europe.
Firefox 1.0 had surpassed Internet Explorer 5 in early 2005 with Firefox 1.0 at roughly 8 percent market share.
An article notes at the release of Internet Explorer 7 in October 2006 that "IE6 had the lion's share of the browser market with 77.22%. Internet Explorer 7 had climbed to 3.18%, while Firefox 2.0 was at 0.69%."
Internet Explorer 7 was released at the same time as Firefox 2.0, and overtook Firefox 1.x by November 2006, at roughly 9% market share. Firefox 2.0 had overtaken 1.x by January 2007, but IE7 did not surpass IE6 until December 2007. By January 2008, their respective version market share stood at 43% IE7, 32% IE6, 16% FF2, 4% Safari 3 and both FF1.x and IE5 versions at less than half a percent.
Approximate usage over time based on various usage share counters averaged for the year overall, or for the fourth quarter, or for the last month in the year depending on availability of reference.
Approximate usage over time based on various usage share counters averaged for the year overall, or for the fourth quarter, or for the last month in the year depending on availability of reference. IE was at its peak in 2003 with 94% of the worldwide internet browsers, but started falling in 2004 and since has hit a 2000s decade low in 2011 with only 49.7% of worldwide internet users.
The ActiveX extension mechanism 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, such as search engine toolbars. Because of the use of COM, it is possible to embed 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.
IE versions, over time, have had widely varying OS compatibility, ranging from being available for many platforms and several versions of Windows to only a few versions of Windows. Many versions of IE had some support for an older OS but stopped getting updates. The increased growth of the Internet in the 1990s and 2000s means that current browsers with small market shares have more total users than the entire market early on. For example, 90% market share in 1997 would be roughly 60 million users, but by the start of 2007 90% market share would equate to over 900 million users. The result is that later versions of IE6 had many more users in total than all the early versions put together.
The release of IE7 at the end of 2006 resulted in a collapse of IE6 market share; by February 2007, market version share statistics showed IE6 at about 50% and IE7 at 29%. Regardless of the actual market share, the most compatible version (across operating systems) of IE was 5.x, which had Mac OS 9 and Mac OS X, Unix, and most Windows versions available and supported for a short period in the late 1990s (although 4.x had a more unified codebase across versions). By 2007, IE had much narrower OS support, with the latest versions supporting only Windows XP Service Pack 2 and above. Internet Explorer 5.0, 5.5, 6.0, and 7.0 (Experimental) have also been unofficially ported to the Linux operating system from the project IEs4Linux.
See also Internet Explorer Mobile. Non-desktop versions of IE have supported Windows CE also.
Early versions of Internet Explorer such as 5 had a compatibility mode to run Internet Explorer 4, though this feature was dropped (also, Internet Explorer for Mac users could still use 4.5 after installing IE 5). While Microsoft claims it is impossible 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 through 7.
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 uses a feature introduced in Windows 2000 called DLL redirection to force it to load older DLLs than the ones installed on the system.
It is also possible to install Internet Explorer via Wine.
After Internet Explorer 7 is installed, an Internet Explorer 6 executable is still available in C:\WINDOWS\ie7, hidden by default. Launching this executable provides the user with the older IE6 interface, however web pages are rendered using the IE7 engine. The IE6 engine can be re-enabled by placing a file named "iexplore.exe.local" into the IE7 folder.
As an alternative to using IE standalone, Microsoft now makes available Microsoft Virtual PC images containing pre-activated copies of Windows XP with either IE 6 or IE 7 installed. Microsoft recommends this approach for web developers seeking to test their pages in the different versions of IE as the standalone versions are unsupported and may not work the same way as a properly installed copy of IE.
While a major upgrade of Internet Explorer can be uninstalled in a traditional way if the user has saved the original application files for installation, 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 proposed during the United States v. Microsoft court case. One of Microsoft's arguments, during the trial, was that removing Internet Explorer from Windows may result in system instability.