^^VM virtual machine. Hypervisor.

"bare-metal" or "type 1" hypervisor: run directly on the hardware
"hosted" hypervisor (sometimes referred to as a "type 2" hypervisor): requires an existing operating system to be installed. It can thus run alongside existing applications on that host
Host operating system (host OS).: This is the operating system of the physical computer on which a hosted hypervisor is installed.
Guest operating system (guest OS): This is the operating system that is running inside the virtual machine.

VirtualBox e' la VM suggerita da Sage