Technology is not an end in itself, but a way of satisfying human wants. It shows us how to solve the age-old economic problem of surviving and pros­ pering in a hard world. But to optimize the benefits of technological advance requires an understanding of how it happens. The purpose of this book is to provide some of that understanding. The subject is so enormous and so intertwined with every human activity that a small selection of it, and that from a special viewpoint, is inevitable. The selection of subject matter has been, of course, conditioned by what interests me and is somewhat heterogeneous. However, it is connected by two major themes. The first is that it emphasizes the dynamic nature of technology, in the sense that it must be approached as a process evolving in time that can often be described in quantitative terms. The second is that I have chosen topics that I believe are essential for a strategic sense of how to plan for, execute, and respond to technological change. These two themes complement each other because the strategic sense requires an appreciation of the dynamics and the dynamics naturally lead to a consideration of how to deal with technology so that it can be used to achieve human objectives. The unifying thought behind the book is that technological change has a systemic as well as an idiosyncratic aspect.