A virtual machine is completely isolated guest operating system installation within a normal host operating system. Virtual Machine Operating system creates illusion of multiple processors each capable of executing independently. Virtual machines are separated into two major categories, based on their use and degree of correspondence to any real machine.
A virtual machine provides a complete system platform which supports the execution of a complete operating system. Multiple operating system can co-exist on the same computer, in strong isolation form each other. The virtual machine can provide that is somewhat different form that of the real machine.
The process of virtual machine is designed to run a single program, which means that it supports a single process. It’s purpose is to provide a platform independent programming environment that abstracts away details of the underlying hardware or operating system and allows a program to execute in the same way on any platform.