Icon

An icon is a small, visual representation of a concept based on similar physical properties, shared behaviours, or relationships.  One of the common applications of an icon is in the modern computer's Graphical User Interface (GUI).  Rather than purely text menus and buttons, we now have visual metaphors for the functions of our computer such as a CD for a music player.

Computer Icons have generally maintained some amount of likeness to the physical world. For example, a CD is like an music player because it contains music. The advantage of a likeness-based visual language is it's easy adoption. Users can quickly associate known nouns and verbs with new ones. In fact, the whole graphical operating system is based on metaphors: windows, files, folders, pages, trash cans, etc.

Several disadvantages exist from the use of likeness-based icons.  First, eventually the metaphor used for the picture no longer applies.  For example, music is being delivered less often on CD and more often over the web, so a CD no longer applies.  Second, new ideas can be limited by older constructs and ways of thinking about the world.