Although the surface electrocardiogram (EKG) was invented in 1903, it continues to be today, more than a century later, an essential tool used by clinicians for the detection and diagnosis of numerous cardiac conditions. Because of its high importance in the clinical management of many patients across vast areas of medical and surgical specialties, it is not too surprising that the medical community has invested, over many decades, a lot of time, effort, and resources into training physicians, nurses, and other allied professionals on how to obtain, troubleshoot, and interpret EKGs. Like most tasks in life, learning how to read EKGs requires time and practice, eventually allowing the expert reader to rely more on pattern recognition to spot abnormalities and make a diagnosis rather than on a step-by-step, systematic reading. With of all these considerations in mind, we have compiled over many years, 106 relevant EKGs that cover most topics of interest (arrhythmias, conduction abnormalities, electrolyte imbalances, etc.), providing a clinical vignette for each case, a succinct interpretation of the findings, a mechanistic explanation of these findings, and often offering insight into possible treatment options. From the outset and throughout the process of putting together this book, we have kept in mind the needs and desires of our potential readers, who include medical students, residents in internal medicine or anesthesia, general cardiology and electrophysiology fellows, as well as registered nurses, EKG technicians, and other allied professional, such as nurse practitioners and physician assistants. Our ultimate goal with this book is to give current and future health professionals a tool that will provide them with the know-how and confidence to hold an EKG tracing in their hand, troubleshoot it, read it, and move on to delivering high-level care to patients. Academic life in medicine stands on three essential pillars: (1) We strive to improve patient outcomes through sound clinical care; (2) We advance knowledge through innovative research; and (3) We perpetuate knowledge through tireless and consistent teaching and training. This book is our small contribution to this third and most important pillar of academic medicine.