Mechanisms of energy transfer are relatively easy to implement in the laboratory; in fact, there are popular computer programs that take the spectra of the donor-acceptor pairs and yield plots of the derived perimeters such as separation distances. But without a critical understanding of the assumptions of an individual theory of an energy transfer mechanism, the derived outputs are deeply confounded, and false conclusions and interpretation of the data are prevalent. This example serves to illustrate the importance of understanding the assumption of each theory, each experimental method, and the required subsequent validation of the theoretical assumptions and their relevance to the experimental conditions. I think that the chapters contained within Molecular Fluorescence contain the prescribed critical description of the physics, chemistry, and instrumentation of luminescence that helps the reader to avoid the common errors of the misuse of the theory and applications of luminescence techniques. The balance between theory and application is excellent. The second edition presents many of the modern fascinating and useful applications of molecular spectroscopy on the scales of single molecules, molecular sensors, molecular structures, tissues, organs, and whole organisms, and all of these developments greatly support fundamental scientific research and medical applications. Molecular Fluorescence is a comprehensive textbook and reference book that provides a deep and critical analysis of this evolving field.