Our understanding of cell structure and function derives from applications of a variety of physical and life science disciplines, methods and models to an important physiological process, namely, the exchange and transport of ions and molecules across biological membranes. We know that ion transport through membranes arises from a diversity of interrelated and interactive physical and chemical phenomena over a wide range of spatial and temporal scales. Among these phenomena common to all cellular structure and function include metabolism, kinetics of molecules, chemically mediated alteration of cell membrane electrical potential, membrane ion conductance, electrical signal propagation, and modulation by chemo- and mechanoreceptive mechanisms. This review focuses on the unique information contained in fluctuations in electrical properties associated with cell membrane ion transport.