About Internet Explorer 9
Windows Internet Explorer 9 (abbreviated as IE9) is the current version of the Internet Explorer web browser from Microsoft. It was released to the public on March 14, 2011 at 21:00 PDT.
Internet Explorer 9 also supports the HTML5 video and audio tags and the Web Open Font Format. Microsoft has released Internet Explorer 9 as a major out-of-band version that is not tied to the release schedule of any particular version of Windows, unlike previous versions.
The system requirements for Internet Explorer 9 are Windows 7, Windows Server 2008 R2, Windows Vista Service Pack 2 or Windows Server 2008 SP2 with the Platform Update. Windows XP and earlier are not supported. Internet Explorer 9 is the last version of Internet Explorer to be supported on Windows Vista; Internet Explorer 10 will only be supported on Windows 7 and later. Both IA-32 and x64 builds are available.