In both the business and personal environments, the question is no longer whether to use software, but which software to choose. In such decision processes, the usability of the software is often not an explicit requirement, but implicitly has a high influence on the selection decision. Excellent usability and positive user experience can only be achieved by knowing and understanding the user's goals, hidden needs, and cognitive abilities. In computer science, we address these challenges in the research area of Human-Computer Interaction (HCI): Besides the choice of the "right" technology, the consideration of the users and their needs is fundamental for the later success of the service or product. However, usability is neither an inherent property of software, nor can usability as a software feature be developed separately at a certain point in time. Usability always exists in a specific usage context, and this context must be clearly understood. Furthermore, in order to improve usability, it is necessary to adapt the entire software development process. The goal should be to ensure that the software, despite its complex functionality and wealth of information, is suitable for use by the target group. Depending on the development phase and the project situation, we can select and apply different principles and methods in our development process to achieve this goal. In the Human-Computer Interaction I course, you will learn and apply these principles and methods to create a positive user experience.