Both in the business environment and for private use, the question nowadays is no longer whether software should be used, but which software to choose. In such decision processes, the usability of the software is often not an explicit requirement, but implicitly it 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, their hidden needs, and also their cognitive abilities. In computer science, we address these challenges in the research area of Human-Computer Interaction (HCI): Besides choosing the "right" technology, considering the users and their needs is fundamental for the later success of the service or product. However, usability is neither a characteristic inherent in software nor can usability, as a software feature, be developed separately at a certain point in time. Usability always stands in a particular 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 is suitable for use by the respective target group despite its complex functionality and wealth of information. Depending on the development phase, and the project situation, we can select and apply different principles and methods in our development process to reach that goal. In the course "Human-Computer Interaction I", you learn and apply these principles and methods to create a positive user experience.