The number ofbooks on databases is very large. Thus, our decision to yet add another book to the body of literature requires some justification. However, even a cursory glance through this book will show that we have taken a rather different approach indeed when compared to monographs on databases. First, material ties together the well-known relational model with the newer and not yet as solidly established object oriented one and leads to data models for hypermedia system. This is unique and timely: the chaos on the World Wide Web is getting out of hand, and one ofthe main reasons is that the underlying data model is too weak. Second, the book is full of illustrations. And those illustrations are not only available in printed form, but also on a CD ROM. Actually, much more is true: for each ofthe 26 chapters, electronic courseware is available, one lesson per chapter. Third, the lessons described contain explanations that are easier or better to understand than those provided in the printed chapter, since a number ofdynamic and interactive features are used. Fourth, the lessons can be used in a variety ofmodes: as complement for the book; as stand-alone material instead ofthe book; as slides for the lecturer; and as help for the student. And, as explained below they can be easily modified.