Microsoft Internet Explorer is a web browser developed by Microsoft and included as part of the Microsoft Windows line of operating systems starting in 1995.
After the first release for Windows 95, additional versions of Internet Explorer were developed for other operating systems: Internet Explorer for Mac and Internet Explorer for UNIX (the latter for use through the X Window System on Solaris and HP-UX).
Only the Windows version remains in active development; the Mac OS X version is no longer supported.
It has been the most widely used web browser since 1999, peaking at nearly 90% market share with IE6 in the early 2000s—corresponding to over 900 million users worldwide by 2006.
Though released in 1995 as part of the initial OEM release of Windows 95, Internet Explorer was not included in the first retail, or shrink-wrap, release of Windows 95.
The most recent release is version 7.0, which is available as a free update for Windows XP with Service Pack 2, and Windows Server 2003 with Service Pack 1, and is included with Windows Vista.
Versions of Internet Explorer prior to 6.0 SP2 are also available as a separate download for versions of Windows prior to Windows XP.
An embedded OEM version called Internet Explorer for Windows CE (IE CE) is also available for WinCE based platforms and is currently based on IE6.
Another Windows CE/ Windows Mobile browser known as Pocket Internet Explorer is from a different codebase and should not be confused with desktop versions of the browser.