Navigating the Maze of Windows Versions

When Microsoft announced Windows 10 last year, there were many comments around the fact that “Windows 10 is the last version of Windows.” However, most technical folks understand it does not mean Microsoft will stop working, improving and releasing new versions. It just means that it got much harder, especially for IT administrators, to identify and understand what is actually running on their devices.


Codenames are commonly used in software development to identify upcoming/future releases. Microsoft is no different:

  • Threshold 1 – First Windows 10 release, July 2015 for Desktop only
  • Threshold 2 – Follow on releases for both desktop and mobile devices, November 2015
  • Redstone 1 – Upcoming major update to Windows 10 (all platforms), Summer 2016
  • Redstone 2 – Follow on release to all platforms, date is TBD

As you can see, there is a pattern where large features come every summer and followed by a release with fixes, minor features, and items that didn’t make it into the Summer release. I have seen speculations in the press that Redstone 2 might be pushed out to Spring 2017, but unless we see Microsoft confirm or deny, I would expect the pattern to stay the same.

Now, how can IT admin determine what version of Windows is running on a specific device? The best way is to look for “build string.” This is information that is stored in the registry of each device:

HKLM\Software\Microsoft\Windows NT\CurrentVersion

And we will find there:

BuildLab:   10240.th1.150729-1800

BuildLabEx: 10240.16412.amd64fre.th1.150729-1800

From the information above, we can see this is RTM (GA in MobileIron’s lingo) build because it has the “10240” designation. You can also see the TH1 information, pointing to the specific Codename and the date of July 29th 2015 when Microsoft shipped TH1.

The extended field is useful when dealing with “preview” or beta builds. Here is an example from my test device:


You can see that I am running build “14385,” that the build is 64 bit (AMD64), and that it is a “FREE” build, not checked (explanation of checked vs free), it is Redstone 1.

If you want to find out what changes each build has at a high level, I suggest Wikipedia.


Tomas Vetrovsky