Windows Internet Explorer (formerly Microsoft Internet Explorer, commonly abbreviated IE or MSIE) is a series of graphical web browsers developed by Microsoft and included as part of the Microsoft Windows line of operating systems, starting in 1995. It was first released as part of the add-on package Plus! for Windows 95 that year. Later versions were available as free downloads, or in service packs, and included in the OEM service releases of Windows 95 and later versions of Windows.
Internet Explorer has been the most widely used web browser since 1999, attaining a peak of about 95% usage share during 2002 and 2003 with Internet Explorer 5 and Internet Explorer 6. Since its peak of popularity, its usage share has been declining in the face of renewed competition from other web browsers, and is currently 40.9% as of June 2011. It had been slightly higher, 43.55% as of February 2011, just prior to the release of the current version. Microsoft spent over $100 million USD per year on Internet Explorer in the late 1990s, with over 1000 people working on it by 1999.
Since its first release, Microsoft has added features and technologies such as basic table display (in version 1.5); XMLHttpRequest (in version 5), which aids creation of dynamic web pages; and Internationalized Domain Names (in version 7), which allow Web sites to have native-language addresses with non-Latin characters. The browser has also received scrutiny throughout its development for use of third-party technology (such as the source code of Spyglass Mosaic, used without royalty in early versions) and security and privacy vulnerabilities, and both the United States and the European Union have alleged that integration of Internet Explorer with Windows has been to the detriment of other browsers.