Want to learn something that will blow your mind? The latest Windows 10 10565 Insider preview build will let users run it inside another version of the OS ... sort of. The new feature that's being tested is called nested virtualization, which will allow for a virtual machine version of Windows 10 to run inside another virtual machine.
Here's the technical breakdown of how this works:
"In essence, this feature virtualizes certain hardware features that are required to run a hypervisor in a virtual machine. Hyper-V relies on hardware virtualization support (e.g. Intel VT-x and AMD-V) to run virtual machines. Typically, once Hyper-V is installed, the hypervisor hides this capability from guest virtual machines, preventing guests virtual machines from installing Hyper-V (and many other hypervisors, for that matter). Nested virtualization exposes hardware virtualization support to guest virtual machines. This allows you to install Hyper-V in a guest virtual machine, and create more virtual machines "within" that underlying virtual machine."
Microsoft says nested virtualization in Windows 10 will only work with Hyper-V; other hypervisors don't currently support it. It also says that this feature is in preview mode, which means there are "plenty of known issues, and there is functionality which we still need to build." However, it's still mind-blowing to think that you can run a version of Windows 10 inside another version.