There’s an interesting article at CloudTweaks today on the difference between “virtualization” and “cloud computing” — which are often conflated.
Virtualization is a systems admin and data management tool that has many technical uses; most of which have nothing to do with the cloud. The technology allows enterprises to use a single piece of physical hardware, to perform the work of many. Multiple operating system instances running on one hardware device are far more economical than a single piece of hardware for every server task. Still, there is no direct link to the cloud from pure virtualization.
Cloud computing, on the other hand, is access through the Internet to business applications running in a non-local environment. Cloud computing can certainly take advantage of virtualization but cloud computing can be (and has been) accomplished without the use of virtualization.