Virtualization: Climate
Before virtualization became publicly available, the idea of one application per server resulted in server sprawl.
Virtualization: Hypervisor
A hypervisor is software between the physical hardware and the virtual machines.
Virtualization: Virtual Machines
A virtual machine is flexible, as its physical form is a set of files, configuration file, and virtual disk files.
Virtualization: Storage
Storage virtualization abstracts the physical resources, and a logical representation of them is presented to virtual machines by the hypervisor