Virtual Machine: the operating system that makes it possible to use software to simulate the functionality of the other computers with 2 or more computers, virtual, nested in a single computer.
Virtual Machine is an operating system that makes it possible to use the software. To simulate the operation of the computer. Similarly, there are two or more computers. Stacked in a single computer.
Virtual Machine operating system that can use the software. For the simulation of other computer virtual machine computer 2 or so. Nested in the only computer .