A virtual machine is a software computer that, like a physical computer, runs an operating system and applications.

A virtual machine contains a display, a hard disk or disks, one or more processors, memory, a CD/DVD drive, a network adapter, and a USB controller.

The virtual machine runs in a window on your Mac. You install an operating system and applications in the virtual machine and operate it as you would a physical computer. An operating system cannot distinguish between a virtual machine and a physical machine, nor can applications or other computers on a network. Whatever you can do with a physical machine (install software, save files, add additional drives, and so on) you can do with a virtual machine.

Virtual machines are completely independent from their underlying physical hardware. For example, you can configure a virtual machine with virtual components that are completely different from the physical components that are present on the underlying hardware. Virtual machines on the same physical host can run different kinds of operating systems (Windows, Linux and others).