Take a quick look at what Fusion does and how it works.
What Fusion Does
Fusion enables you to run your Windows applications and PC-only devices on your Intel-based Mac. You can run multiple operating systems and applications at the same time, along with your Mac applications. The operating systems and applications are isolated in secure virtual machines.
How Fusion Works
Fusion maps the physical hardware resources to the virtual machine’s resources, so each virtual machine has its own processor, memory, disks, I/O devices and so on. Each virtual machine is the full equivalent of a standard x86 computer, although it is represented in a single file package on the Mac.
After you install Fusion and create a virtual machine, you can install and run complete, unmodified operating systems, and associated application software in the virtual machine, just as on a physical PC. Operating systems you can use include Windows, Linux, and Mac OS X. Fusion offers the benefits of having a second PC without its added expense, physical setup, and maintenance.
The operating system of the computer on which you run Fusion is called the host. Mac OS X and Mac OS X Server are the only hosts supported for Fusion. The virtualized operating system you run inside Fusion is called the guest.