The rapid progress of the research field of quantum chaos and its application called for a book that keeps students abreast of the new developments and at the same time provides a solid basis in subjects which form the canon of the field. This book discusses the following topics: spectral statistics and their semiclassical interpretation in terms of the Gutzwiller trace formula, quantum chaos and its application in mesoscopic physics, spectral statistics and conductance fluctuations and quantum chaos in systems with many degrees of freedom. The line of this book connects and continues past and present achievements and prepares the ground for a future full of intriguing and important developments.