<P> In hardware virtualization , the host machine is the actual machine on which the virtualization takes place , and the guest machine is the virtual machine . The words host and guest are used to distinguish the software that runs on the physical machine from the software that runs on the virtual machine . The software or firmware that creates a virtual machine on the host hardware is called a hypervisor or Virtual Machine Manager . </P>
which tool requires an underlying operating system in order to create and manage virtual machines
hypervisor or Virtual Machine Manager