Interface Metaphors
Metaphor n. the application of a word or phrase to an object or concept which it does not literally denote, in order to suggest comparison with another object or concept, as in "A mighty fortress is our God." (Webster's Encyclopedic Unabridged Dictionary of the English Language)
It is often effective to employ a form of human-computer interface in which an aspect of the real world is used to symbolize and (hopefully) simplify an aspect of the computer program with which a user is interacting.
Theoretical Foundations of Multimedia Chapter 7