Biophysics is an interdisciplinary subject—a ''bridge'' between physical and natural sciences. Recent advances in physical sciences and progress that are taking place in biological and medical sciences, are making them more datarich and has brought the subject of Biophysics to the center stage. The subject of this book is thus conceived and presented taking into account these developments to reach out to the students and scholars with biological and medical background, to make them knowledgeable about the physical principles and techniques that are becoming an integral part of their subjects and to inculcate the quantitative approach in natural sciences, which is the essential part of physical sciences. This book is also aimed at the physical sciences faculties, to bring to their awareness, the structural and functional aspects of biological entities and the complexity and the emerging trends in natural sciences. In essence, this book is to reach out to the students of physical sciences also, whose convergent interest is in the biological/medical sciences.