This document discusses human-computer interaction (HCI), including its definition as the study of how humans interact with computers. It outlines the three main parts of HCI - the user, computer, and their interaction. The document then describes different types of interfaces like graphical, menu-driven, voice-driven and touch interfaces. It also covers current technologies, inventions in HCI, its uses across various fields, and advantages and disadvantages. In conclusion, it emphasizes the importance of usability and designing interactive products with the user in mind.