This book integrates concepts and methods from physics, biology, biochemistry and physical chemistry into a standalone, unitary text of biophysics that aims to provide a quantitative description of structures and processes occuring in living matter. The book introduces graduate physics students and physicists interested in biophysics research to "classical" as well as emerging areas of biophysics. The advanced undergraduate physics students and the life scientists are also invited to join in, by building on their knowledge of basic physics. Essential notions of biochemistry and biology are introduced, as necessary, throughout the book, while the reader's familiarity with basic knowledge of physics is assumed. Topics covered include interactions between biological molecules, physical chemistry of phospholipids association into bilayer membranes, DNA and protein structure and folding, passive and active electrical properties of the cell membrane, classical as well as fractal aspects of reaction kinetics and diffusion in biological systems, structural and functional aspects of molecular machines (including channels, ion pumps, and light-harvesting antenna), as well as fundamental aspects of proteins association in solutions and in living cells.