This book shows step by step how to develop, implement (engineering) and operate (administration) technical systems efficiently and effectively. To this end, it first explains how complex real systems are simplified, i.e. modeled, in order to make their relevant properties visible. This is done in an interdisciplinary manner by taking into account not only technological but also sociological and psychological aspects. Five generally valid process models are then explained, which are sufficient to design and control systems in all their life phases. Finally, the problem-solving cycle is explained in detail. For each phase of development, it explains what should be done when, why and how in order to successfully complete the project. References to project management are also made. All the models, methods, procedures and tools explained have already proven themselves in practice many times over. The book is therefore suitable as a guide for practitioners and for academic teaching. Above all, those who not only want to know what they should do, but also want to understand why one works better than the other, will not only find appropriate explanations, but also numerous suggestions that encourage constructive and critical thinking and enable innovation.