The path for developing an internationally usable product with a human-machine interface is described in this textbook, from theory to conception and from design to practical implementation. The most important concepts in the fields of philosophy, communication, culture and Ethnocomputing as the basis of intercultural user interface design are explained. The book presents directly usable and implementable knowledge that is relevant for the processes of internationalization and localization of software. Aspects of software ergonomics, software engineering and human-centered design are presented in an intercultural context; general and concrete recommendations and checklists for immediate use in product design are also provided. Each chapter includes the target message, its motivation and theoretical justification as well as the practical methods to achieve the intended benefit from the respective topic. The book opens with an introduction illuminating the background necessary for taking culture into account in Human Computer Interaction (HCI) design. Definitions of concepts are followed by a historical overview of the importance of taking culture into account in HCI design. Subsequently, the structures, processes, methods, models, and approaches concerning the relationship between culture and HCI design are illustrated to cover the most important questions in practice.