This volume provides a unified treatment that interprets the salient features of the experimental relationship between the structure and function of ion channels. This treatment encompasses both the voltage-gated ion channels in charge of excitable membranes and the smaller antimicrobial peptide ion channels. The book requires only an understanding of basic physical chemistry and mathematics, and will be accessible to graduate students, research workers, and teachers in biophysics, bioelectrochemistry, biology, biochemistry, pharmacology, physiology, bioanalytical chemistry, and related disciplines. It provides insights into the basic principles required to understand why and how a combination of electrophysiological and electrochemical concepts and tools is essential in clarifying the mode of ion transport across biomembranes through ion channels. In this respect, this book bridges the gap arising from the difficulties encountered by biologists in understanding concepts of electrochemistry, and vice-versa, to the benefit of all life scientists.