Windows 8.1
Windows 8.1 is a no longer supported version of Microsoft Windows and the second version of Windows 8.x. It was released on October 17, 2013, the same day as Windows Server 2012 R2. It is a new version of the Windows NT 6.x line, since it changes the version number from 6.2 to 6.3. It is a free update for Windows 8 that can be found in the Windows Store. When Windows 10 was released, Windows 8.1 could be upgraded to Windows 10 for free.