Internet Information Server (IIS) software

Description
Table of Contents
Operations
How to obtain the version of IIS installed
How to do it

The version of the IIS installed is directly related to the version of the Windows operating system installed:

Windows Server 2000      5.0
Windows XP Professional  5.1
Windows Server 2003      6.0
Windows Vista            7.0
Windows Server 2008      7.0
Windows Server 2008 R2   7.5
Windows 7                7.5
Windows Server 2012      8.0
Windows 8                8.0

This is detailed described on IIS version.