Object-oriented analysis and design (OOA & D) has during the 1990s become the dominant method for describing computer-based systems. With this book, we have sought to provide a widely applicable presentation of OOA & D in Danish. Our method is at once original and proven. The method presents a new overall view of analysis and design, which makes it easy for the reader to understand these important activities as a whole. However, many individual parts of the method are derived from other methods. We have carefully selected the parts that have proven to work best in practice. We have strived to provide a comprehensive presentation of key principles. Analysis and design are otherwise often handled fragmented. The design of the logical core of the computer system is traditionally governed by functional considerations and characterized by the literature on programming and modeling. The design of the user interface and the interaction with the environment are guided by practical considerations and primarily dealt with in the literature on human-machine interaction and user-friendliness. The design of the system's architecture is often governed solely by technical considerations. In this book, we look at all the essential aspects of analysis and design. The four central parts of the book systematically review the problem area of ??the computer system, its scope, its architecture and its components. We have also strived to provide a methodological presentation. The main emphasis is on principles, concepts and ways of thinking. Often, analysis and design books are tied to a particular notation with associated charting techniques and CASE tools. It lends itself to fruitless religious wars, and it creates dependence on specialized commercial products. In this book, we have chosen as a notation the Unified Modeling Language, UML, which is on its way to becoming standard in the field. This will give the reader access to a wide range of development tools. Finally, we have endeavored not to write a book on object-oriented programming. The use of OOA & D creates clarity about the requirements for a computer system and a qualified basis for its implementation. But the method presupposes that the continued work is carried out by competent programmers who can utilize the facilities in modern programming environments to achieve high productivity and high quality. We recommend that the analysis document should contain a concise but complete description of the requirements for the system, and that the design document should be concise, provide an overview of the system parts and their interactions, and answer the key design questions. OOA & D can be used for practical system development and for teaching. One of the book's target groups is system developers who want support for the introduction of object-oriented technology or inspiration for personal professional development. The second target group is students in the computer science, computer science and data engineering programs, as well as students in other programs that require practical and theoretical skills in system development.