The interaction of electromagnetic waves with matter in the frequency range between 10-6 and 1012 Hz is the domain of broadband dielectric spectroscopy. In this extraordinarily extended dynamic range molecular and collective dipolar fluctuations, charge transport and polarisation effects at inner and outer boundaries take place and determine the dielectric properties of the material being studied. Hence, broadband dielectric spectroscopy enables one to gain a wealth of information on the dynamics of bound (dipoles) and mobile charge carriers depending on the details of a molecular system. It is the intention of this book to be both an introductory course to broadband dielectric spectroscopy as well as a monograph describing recent dielectric contributions to current topics. In this respect the book will correspond to the needs of graduate students but also to specialized researchers, molecular physicists, polymer scientists and materials scientists in academia and in industry.