Human-computer interaction (HCI) design is a field of study that focuses on the interaction between humans and computers. It is a broad discipline that encompasses many different aspects of design, such as accessibility. In the context of UX design, human-computer interaction design is concerned with creating user interfaces that are effective, efficient, and enjoyable to use. This involves understanding the user's needs and goals, and designing an interface that meets those needs in a way that is both easy and intuitive to use.