What is Virtualization in software testing

Hello all,
I have recently come across a term called " Virtualization" and " Virtualization for Software Testing"..So for that I went through some of the article and one article from Redhat was very good in explaining these terminologies...."Virtualization allows multiple operating system instances to run concurrently on a single computer;it is a means of separating hardware from a single operating system. Each “guest” OS is managed by a Virtual Machine Monitor (VMM), also known as a hypervisor. Because the virtualization system sits between the guest and the hardware, it can control the guests’ use of CPU, memory, and storage, even allowing a guest OS to migrate from one machine to another"............This is the definition....tough to understand ......simple.....For ex...If u want to test a software product in operating systems like Windows XP, vista, Mac, Linux and Unix, then u have to get 5 systems and install an OS in a machine.....so the cost here is very high...for that in the organization, One person uses vista and other person uses Mac and another person uses Linux....U need to create a Guest login in each OS and maintain it from a single machine which will have one software called VMM (virtual machine monitor) with the help of internel network or even accessing with out side network.....with the help of VMM software u can control the memory of all 4 or 5 system and even u can migrate from one machine access to other.....so this is one of the emerging trends in IT across all industries.

Thanks & Regards,
Varun
dayavarun@gmail.com