It is not always the case that the subject of a scientific book and its relevance to everyday li fe are so timely. Photobiology and its si ster subject Radiobiology are now a must for understanding the environment we live in and the impact light, ultraviolet light, and radiation have on all aspects of our life. Photobiology is a true interdisciplinary field. Photobiology research plays a direct role in diverse fields, and a glance at the topics of the symposia covered in this book by over 100 articles shows the breadth and depth of knowledge acquired in fundamental research and its impact on the major issues and applied problems the world is facing. Half a century of photobiology research brought about an understanding of the importance of light to life, both as a necessary source of energy and growth as weIl as its possible dangers. Research in photochemistry and photobiology led to the discoveries of ceIlular repair mechanisms of UV induced damages to DNA and this led to understanding of the effects of hazardous environmental chemieals and mutagenecity , and to the development of genetic engineering. This topic was given due emphasis in several symposia and chapters in this book.