virtualization:    The act of integrating one or more (back end) services or functions with additional (front end) functionality for the purpose of providing useful abstractions. Typically, virtualization hides some of the back end complexity, or adds or integrates new functionality with existing back end services. Examples of virtualization are the aggregation of multiple instances of a service into one virtualized service, or to add security to an otherwise insecure service. Virtualization can be nested or applied to multiple layers of a system.

See also: block virtualization, file virtualization, processor virtualization