"Let's first spend a little time understanding why
virtualization is important and the role that hypervisors play.
(And for more information on both topics, see the Resources
"Virtualization, in the context of this article, is the process
of hiding the underlying physical hardware in a way that makes it
transparently usable and shareable by multiple operating systems.
This architecture is more popularly known as platform
virtualization. In a typical layered architecture, the layer that
provides for the platform virtualization is called the hypervisor
(sometimes called the virtual machine monitor, or VMM). Each
instance of a guest operating system is called a virtual machine
(VM), because to these VMs, the hardware is virtualized to appear
as dedicated to them. A simple illustration of this layered
architecture is shown in Figure 1."