Almost all life depends on light for its survival. It is the ultimate basis for the food we eat (photosynthesis), and many organisms make use of it in basic sensory mechanisms for guiding their behaviour, be it through the complex process of vision, or by the relatively more simple photosens­ itivity of microorganis~urthermore, light has profound implications for the field of medicine, both as a cause of disease (ie UV damage of DNA), and as a therapeutic agent (ie photodynamic therapy). These and other processes are the basis for the science of photobiolog~ which could be defined as the study of the effects of (visible and ultraviolet) light (from both the sun and artificial sources) on living matter. By its very nature, therefore, it is a multidisciplinary science involving branches of biology, chemistry, physics and medicine. This book contains a selection of papers which have been chosen to highlight recent advances in the various disciplines that make up photo­ biology. Although no book on photobiology can hope to be comprehensive, we hope that this volume includes a representative sample of much of what is new in the field. It is, however, inevitable that some areas will be better represented than others reflecting the biases of conference org­ anisers and editors.