It is now well established that all living systems emit a weak but permanent photon flux in the visible and ultraviolet range. This biophoton emission is correlated with many, if not all, biological and physiological functions. There are indications of a hitherto-overlooked information channel within the living system. Biophotons may trigger chemical reactivity in cells, growth control, differentiation and intercellular communication, i.e. biological rhythms. The basic experimental and theoretical framework, the technical problems and the wide field of applications in the food industry, medicine, pharmacology, environmental science and basic sciences are presented in this book, which also includes the rapidly growing literature. This book is written by the most outstanding international scientists familiar with this topic who have been working in this field for many years.