In order to be successful, engineers have to master and to be able to apply a wide range of descriptive knowledge, such as knowledge about the properties of materials and the workings of different kinds of constructions. That type of knowledge is similar to scientific knowledge, and its nature has been studied extensively in the philosophy of science. But descriptive knowledge is not enough. In addition, norms play important roles in engineering and technology, and engineers need to have knowledge of those too. It is the purpose of this book to clarify what these roles are and to investigate to what extent they have consequences for the nature of technological knowledge. In this introduction, we will confine ourselves to first describing the various types of norms in technology. We will then show how norms are related to central concepts in engineering, which is illustrated by a discussion of the notion of risk. At the end of this introduction, we will present the outline and architecture of the book.