Microsoft Internet Explorer 5 (IE5) is a graphical web browser and one of the main participants of the first browser war. Its distribution methods and Windows integration were involved in the "United States v. Microsoft Corp." case. It is included with Windows 98 SE and Windows Me and it is the last version of Internet Explorer compatible with Windows 3.1x, Windows NT 3.x and Windows 95. Although Internet Explorer 5 ran only on Windows, its siblings Internet Explorer for Mac 5 and Internet Explorer for UNIX 5 supported Mac OS X, Solaris and HP-UX.