Virtualization is to create 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. Devices, applications and human users are able to interact with the virtual resource as if it were a real single logical resource.
This is the amalgamation of multiple network storage devices into what appears to be a single storage unit.
This is the partitioning of a single server into serveral small virtual server.
Operating System Virtualization
This is a type of server virtualization technology which works at the operating system (kernel)layer.
This is the ability to create logical, virtual networks that are decoupled from the underlying network hardware to ensure the network can better integrate with and support increasingly virtual environments.