Biophotonics is a rapidly increasing field of current scientific research and applications, based on the discovery of biophotons, a permanent, weak photon current emanating from all living systems. The biophoton emission reflects some, if not all, of the essential biological and physiological activities in biological systems. Biophotonics provides a powerful tool for investigating these electromagnetic interactions. The theoretical approach requires holistic models of living systems, rather than local analytical models. Consequently, these new insights into living matter create a new basis of "integrative biophysics" that is concerned with the questions of regulation, communication and organization of biological systems. Most of the specialists working in this interdisciplinary field of physics, biology, biophysics and medicine are associated with "The International Institute of Biophysics" (IIB), in Neuss, Germany, where basic research and possibilities for applications are coordinated. The growth in this field is indicated by the increase in financial support, interest from the scientific community and frequency of publications. Audience: The scientists of IIB have presented the most essential background and applications of biophotonics in these lecture notes in biophysics, based on the summer school lectures by this group. This book is devoted to questions of elementary biophysics, as well as current developments and applications. It will be of interest to graduate and postgraduate students, life scientists, and the responsible officials of industries and governments looking for non-invasive methods of investigating biological tissues.