<P> Virtualization began in the 1960s, as a method of logically dividing the system resources provided by mainframe computers between different applications . Since then, the meaning of the term has broadened . </P> <P> Hardware virtualization or platform virtualization refers to the creation of a virtual machine that acts like a real computer with an operating system . Software executed on these virtual machines is separated from the underlying hardware resources . For example, a computer that is running Microsoft Windows may host a virtual machine that looks like a computer with the Ubuntu Linux operating system; Ubuntu - based software can be run on the virtual machine . </P> <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> <P> Different types of hardware virtualization include: </P>

Which tool requires an underlying operating system in order to create and manage virtual machines