Is it a derivative? I'd say it's the latest version of Windows NT.

That's still the same NT line tho they changed how versions are called after Windows 8.1 which was NT 6.3. Initial Windows 10 release was bumped to NT 10.0 but further versions use year-month and year-half year formats

[1] - https://en.wikipedia.org/wiki/List_of_Microsoft_Windows_vers...

The kernel version number stopped having any meaning in 2000.

It’s the same codebase that was my point. Whether it’s still called Windows NT or whether that name died in the 90s can probably be argued either way.

NT is still the name of the kernel. (ntoskrnl.exe)

I wonder if that is still true for Azure OS.

Kind of,

https://techcommunity.microsoft.com/t5/windows-os-platform-b...

However plenty of Azure infrastructure uses Linux as well,

https://github.com/microsoft/azurelinux

https://azure.microsoft.com/en-us/blog/sonic-the-networking-...

The marketing and front-facing name clearly died. The internal name did not.

I think XP is when the DOS based Win95/98/ME was merged with NT

The Win95 line wasn't really merged, more discontinued. XP had improved DOS/legacy compatibility vs win2000 but not much.

It was never merged. The DOS-based Windows series was just replaced.

Windows 2000 could have just as easily been the OS that replaced the DOS-based Windows series, it was user-friendly and functional enough.

Much of that pre-2000 code remains. But so much more has been added in the last 1/4 century that "the same codebase" is somewhat a matter of perspective.