This document discusses human-computer interaction (HCI). It defines HCI as the study of how people interact with computers and how computers can be designed for successful human interaction. The document also distinguishes between user interfaces, which determine how users give commands and view information on a computer, and HCI, which describes the relationship between humans and computers. Finally, it argues that HCI is important for designing intuitive systems that allow users to interact with computers in a natural way without thinking about the underlying technical details.