Virtualization

Virtualization, in computing, refers to the act of creating a virtual (rather than actual) version of something, including but not limited to a virtual computer hardware platform,operating system  (OS), storage device , or computer network  resources.

Virtualization began in 1960s mainframe computers as a method of logically dividing the system resources provided by mainframes between different applications. Since then, the meaning of the term has broadened.

Different types of hardware virtualization include:

• Full virtualization – almost complete simulation of the actual hardware to allow software, which typically consists of a guest operating system, to run unmodified.
• Partial virtualization – some but not all of the target environment is simulated. Some guest programs, therefore, may need modifications to run in this virtual environment.
• Paravirtualization – a hardware environment is not simulated; however, the guest programs are executed in their own isolated domains, as if they are running on a separate system. Guest programs need to be specifically modified to run in this environment.