Nowadays, when an enormous number of computer
-based systems exist, the human activities are beingcomputer mediated.
Commonly, in designing the interfacesto those systems, the Hu-man Computer Interaction is left behind without consideration.It might be the case where people do not really understand
whatHuman Computer Interaction is, and thus its important role in the Computer Science field. This chapter will, respectively, introducethe Human Computer Interac-tion(in short HCI)‘s theoretical foundations: the definition, the field of HCI and the foundations of HCI. What more aregeneral principles of visual design in HCI will also be reviewed.