I stumbled upon VMware vSphere Hypervisor (ESXi) 6.5 [it's free] today. At first I just thought it was just an alternative to vbox as a VM manager, not an alternative in terms of BOINC using vbox for things like vLHC of course.

Then I noticed it's an .iso so first off I'm curious what operating system it is, and secondly since it is its own OS does that mean it could be more efficient than running a VM manager in your mom and pop operating systems (win7, ubuntu, OSX...)? I'm not feeling like doing the new OS install .iso game right now but if anyone has any feedback on their experience with this series of products I'm interested.

I could easily be way out of my depth with this stuff.