Quantitative elucidation of structural, energetic and dynamic aspects of macromolecular interactions is indispensable for understanding the functional activities of biomolecules and their interactions. The optical spectroscopic methods are not confined to small molecules or macromolecules but permit the studies of even the largest biological systems in their full splendor, including the living cell. In, , expert researchers in the field detail many of the methods which are now commonly used to study properties of individual macromolecules, their complexes, organelles, and cells, using optical spectroscopic techniques. These include methods and approaches for experimental and theoretical analyses of fluorescence properties of the examined systems, single molecule approaches, electronic absorption, and electro-optical analyses of macromolecular interactions, structures, and dynamics. Written in the highly successful (tm) series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step laboratory prools, and key tips on troubleshooting and avoiding known pitfalls.