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. For another long-standing concrete example, see Internet Explorer's poor PNG transparency support, which remained unfixed until Internet Explorer 7

Usage share

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 95% during 2002 and 2003, it has since been in a slow, 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 83% (based on statistics reference). Usage is higher in Asia and lower in Europe. For example, the share is around 94% in Japan, and around 56% in Germany

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.