ached without a fair assimilation of the first. Secondly, the mathematical difficulties of IT and QIT can, largely, be alleviated by making the presentation less formal than in the usual academic reference format. This does not mean oversimplification, but rather skipping many academic caveats, which flourish in most reference textbooks, and which make progression a tedious and risky adventure. Our portrayed telecom scientist only needs the fundamental concepts, along with supporting proof at a satisfactory level. Also, IT and QIT can be made far more interesting and entertaining by use of many illustrations and application examples. With these goals in mind, this book has been organized as a sequence of chapters, each of which can be presented in two or three hour courses or seminars, and which the reader should be able to teach in turn! Except at the beginning, the sequence of chapters presents a near-uniform level of difficulty, which rapidly assures the reader that she or he will be able to make it to the very end. For the demanding, or later reference, the most advanced demonstrations have been relegated into as many Appendices. To lighten the text, an extensive use of footnotes is made. These footnotes also contain useful Internet links, and sometimes bibliographical references. Finally, lots of original exercises with difficulty levels graded as basic (B), medium (M), or tricky (T) are proposed, the set of solutions being available to class teachers from Cambridge University Press. As to the Internet links, one is aware that they do not have the value of permanent references, owing to the finite lifetime of most websites or their locators or addresses (URL). To alleviate this problem, the Publisher has agreed with the author to keep up an updated list of URLs on the associated website: www.cambridge.org/9780521881715 along with errata information. What about the book contents? The first two chapters (1 and 2) concern basic recalls of probability theory. These are purposefully entertaining to read, while th