Virtual Machine

A virtual machine is software that emulates a computer system. Virtual machines can run programs or full operating systems.

There are two major categories of virtual machines:

• System virtual machines: They allow several operating systems to coexist on a single computer, strongly isolated from each other. The software layer that runs this virtualization is called a virtual machine monitor or hypervisor and, broadly speaking, it can run on the host’s bare hardware or on an operating system.

• Process virtual machines: These run as a process inside the operating system by interpreting between the source code and the machine code to run the application, independent of the hardware platform and the operating system. The clearest example is the Java Virtual Machine.