Book excerpt: This book presents a comprehensive and unifying theory to promote the under standing of technical systems. Such a theory is useful as a foundation for a ratio nal approach to the engineering design process, as a background to engineering education, and other applications. The term "technical system" is used to represent all types of man-made artifacts, including technical products and processes. The technical system is therefore the subject (in the grammatical sense of the word) of the collection of activities which are performed by engineers within the processes of engineering design, including generating, retrieving, processing and transmitting of information about products. It is also the subject of various tasks in the production process, including work preparation and production planning, and in many economic considerations, company-internal and societal. In this way, the Theory of Technical Systems is a contribution to science, as in terpreted in the wider, Germanic sense of a "co-ordinated and codified body of knowledge". It brings together the various viewpoints of engineers, scientists, economists, ergonomists, managers, users, sociologists, etc., and shows where and how they influence the forms of engineering products. It also explains the influ ences that a product exerts on its environment. This Theory of Technical Systems should thus interest design engineers, and en gineers involved in production, management, sales, etc. In an interdisciplinary ap plication of value analysis, the Theory of Technical Systems should provide answers to many questions raised in this field.