This chapter introduces a set of case studies that are used in the rest of the book. They encompass well known problem domains in Human-Computer Interaction research and provide a practical focus for the approaches presented in this book. The set of case studies includes case studies concerned with: the controller interface to a (semi-automated) nuclear power plant; a partly-autonomous arrival management interactive system in the domain of air-traffic control; a user interface for new interactive cockpits and an interactive system used in rural and urban areas to maintain wind turbines. The final case study brings an interesting perspective for formal techniques, namely interactive public displays.