Virtualization means to create a virtual version of a device or resource, such as a server, storage device, network or even an operating system where the framework divides the resource into one or more execution environments.
The largest part of time must be taken by testing process but not by the creation of the system backup copies and their configurations or the system recovery after the failure in a result of the unstable work of the software product built.
virtualization enable the optimization of these processes. Several simultaneously started virtual test environments on a single physical machine or group of machines considerably increase the IT infrastructure flexibility and the efficiency of hardware usage.
When it comes to use Virtualization in testing domain,I would say,You have to test your website on a large set of devices and Operating Systems and Its impossible to purchase all those devices to just test a website.That would be a total waste of money.Here where the virtualization comes into play.
We can create virtual machines of all those devices and O.S’s on which we want to test down our application.
there are lot of options out there for using cloud services for virtualization.
I know a website which offers more than 1400 browsers and huge set of VM’s to test your application, named LambdaTest.