This document discusses HCI (human-computer interaction) in the software development process. It explains that HCI is used to create an intuitive interface between users and products. Usability, effectiveness, efficiency, and satisfaction are important traditional usability categories to consider. The software lifecycle involves designing for usability at all stages. Prototyping is discussed as a model where prototypes are built, tested, and refined with user feedback until an acceptable final system is achieved. Design involves understanding users, requirements, and balancing goals within technical constraints.