One goal for the discipline of human-computer interaction is to go beyond the
specifics of guidelines and build on the breadth of principles to develop tested,
reliable, and broadly useful theories. Of course, for a topic as large as user-interface
design, many theories are needed. Some theories are descriptive and
explanatory; these theories are helpful in developing consistent terminology for
objects and actions, thereby supporting collaboration and training. Some theories
are predictive; these theories enable designers to compare proposed designs
for execution time or error rates.