We will discover how to find order parameters, how they „slave“ subsystems, and how to obtain equations for order parameters. This chapter includes methods of treating continuously extended media. We will also discuss the fundamental role of fluctuations in self-organizing systems. Chapters 8 to 10 are devoted to a detailed treatment of selected examples from physics, chemistry, and biology. The logical connection between the different chapters is exhibited in Table 1.1. In the course of this book it will transpire that seemingly quite different systems behave in a completely analogous manner. This behavior is governed by a few fundamental principles. On the other hand, admittedly, we are searching for such analogies which show up in the essential gross features of our systems. When each system is analyzed in more and more detail down to the subsystems, quite naturally more and more differences between these systems may show up.