How does virtualization software work?

Question

I wonder how virtualization software such as VirtualBox or VMWare Workstation works? How can they create a virtual environment that is taken as a separate computer by operating

Answer 1

How does VMWare work: http://www.extremetech.com/article2/0,2845,1624080,00.asp

How does virtualizaton work: http://blog.tmcnet.com/voip-enterprise/tmcnet/how-does-virtualization-work-and-why-is-now-a-good-time-to-check-it-o.asp

Server Virtualization FAQ http://www.itmanagement.com/faq/server-virtualization/