This book introduces the readers to the field of electrophysiology. The exceptional progress of recording techniques paved way for a better understanding of electrophysiological phenomena within the human organs, including cardiovascular, ophthalmologic and neural systems. The introduction of several sophisticated recording and mapping techniques in the field of cardiac electrophysiology made it possible to describe the mechanism of various cardiac arrhythmias. This has even led to the development of techniques to ablate and cure most complex cardiac arrhythmias. However, there is still a long way ahead and this book will be a valuable addition to the contemporary knowledge in subjects related to bioelectricity from plants to the human heart.