The user interface is the part of a computer system that a user sees, hears or otherwise directly enagges with. The field of Human-Computer Interaction includes aspects targeted at improving the user experience of using user interfaces, and the software needed to create them.
Used in Chap. 18: page 273; Chap. 19: page 309; Chap. 20: page 314
Used in glossary entries: Human Computer Interaction