Windows Internet Explorer (formerly Microsoft Internet Explorer; abbreviated to MSIE or, more commonly, IE), 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 has been the most widely used web browser since 1999, attaining a peak of about 95% usage share during 2002 and 2003 with IE5 and IE6.
That percentage share has since declined (with drops to 94%) in the face of renewed competition from other web browsers – Mozilla Firefox most of all. Microsoft spent over $100 million a year on IE in the late 1990s, with over 1,000 people working on it by 1999.
The latest release is Internet Explorer 8, which is available as a free update for Windows XP with Service Pack 2 or later, Windows Server 2003 with Service Pack 1 or later, Windows Vista, and Windows Server 2008, and is planned for inclusion with Windows 7 and Windows Server 2008 R2, except in Europe.
Versions of Internet Explorer for other operating systems have also been produced, including Internet Explorer Mobile (Windows CE and Windows Mobile), Internet Explorer for Mac and Internet Explorer for UNIX (Solaris and HP-UX).