Information retrieval (IR) has changed considerably in recent years with the expansion of the World Wide Web and the advent of modern and inexpensive graphical user interfaces and mass storage devices. As a result, traditional IR textbooks have become quite out of date and this has led to the introduction of new IR books. Nevertheless, we believe that there is still great need for a book that approaches the eld in a rigorous and complete way from a computer-science perspective (as opposed to a user-centered perspective). This book is an e ort to partially ful ll this gap and should be useful for a rst course on information retrieval as well as for a graduate course on the topic. The book comprises two portions which complement and balance each other. The core portion includes nine chapters authored or coauthored by the designers of the book. The second portion, which is fully integrated with the rst, is formed by six state-of-the-art chapters written by leading researchers in their elds. The same notation and glossary are used in all the chapters. Thus, despite the fact that several people have contributed to the text, this book is really much more a textbook than an edited collection of chapters written by separate authors. Furthermore, unlike a collection of chapters, we have carefully designed the contents and organization of the book to present a cohesive view of all the important aspects of modern information retrieval.

From IR models to indexing text, from IR visual tools and interfaces to the Web, from IR multimedia to digital libraries, the book provides both breadth of coverage and richness of detail. It is our hope that, given the now clear relevance and signi cance of information retrieval to modern society, the book will contribute to further disseminate the study of the discipline at information science, computer science, and library science departments throughout the world.