Virtualization software allows one to run instances of another operating system (or the same type of operating system) on a computer. There is a lot of use for virtualization in the server market (for example, a webhosting company providing ‘private servers’). There are numerous benefits, ranging from security, ‘better’ hardware utilization, and being able to run legacy software on older operating systems.

There are various virtualization software out there with different implementations: VMware, Xen, and Parallels, to name a few.

I’ve tended to stick with VirtualBox, ever since they started supporting x86-64 (EM64T and AMD64).

Why would you use this? Well, if you want to play with Linux but don’t want to install it on your PC, you can install different Linux flavors via VirtualBox and run them on your Windows PC. (Just don’t expect to get good I/O performance running ANSYS through virtualization software.)