A set of visuals, actions and procedures that help a user understand a target domain (e.g. a computer) by exploiting
Knowledge that the user has of a source domain (e.g. office work). One of the most famous user interface metaphors is the desktop metaphor, which introduced the idea that working with a computer is like working at a desktop with folders, a file cabinet, a trash bin etc. Even though frequently criticized for being outdated and for hindering the development of new innovative user interface paradigms, user interface metaphors remain a fundamental component of most modern operative systems.