Human-Computer Interaction (HCI) is the interdisciplinary field studying the design and use of computing systems, focusing on the interface between the user and the machine. It is fundamentally important for Computer Science because it ensures that technically sound solutions are simultaneously usable, effective, and enjoyable, optimizing the user experience (UX). Socially, HCI is critical as it makes technology accessible and productive for everyone, bridging the gap between human needs and technological capability. The course offers an introduction into the basic concepts in HCI, through the following teaching subjects: