It's beautiful of virtual machine live migrating, we can migrate a running virtual machine to another host by this feature.
I think it 's one of the most beautiful feature of virtualization technology.
Summary, the advantage of virtualization:
1> Live migrating/Easy to management,especially for remote.
2> vm is completely isolated from the host
3> Several system can co-exists at the same set of hardware and also the same time.
Of course, there is also disadvantage, that's the virtualization will occupy more calculate resources of the host than running the app directly on it.