This textbook introduces the foundations of human-computer interaction, covering basic psychology and computer technology, models and methods for interface design and applications. It can be used as a text for a course in HCI or as the basis for a curriculum in HCI, with sections of it being taken separately for single course units. Later parts of the book cover more advanced material, but no initial knowledge is assumed. The authors have combined a broad, yet detailed look at HCI from a psychological and computer science perspective, which emphasizes the design of interactive systems. The text is supported by worked examples and exercises of varying difficulty and suggested projects.