Virtualization: Old Technology Offers Huge New Potential
Greg Goth · IEEE Distributed Systems Online · 2007
Essentially, virtualization uses a virtual machine monitor or host called a hypervisor to enable multiple operating system instances to run on a single physical server. The hypervisor can run directly on a given server's hardware platform, with the guest operating system running on a layer above the hypervisor. It can also run within an operating system, with the guest OS running on the third layer above the hardware