Explore the fundamentals of electrocardiography (ECG/EKG) and bipolar limb leads in this comprehensive cardiology lecture. Delve into the meaning of ECG leads, electrode purposes, and diagrammatic representations. Learn about electrical vectors, mean QRS vectors, and conduction processes. Understand how potential events are recorded on ECG machines and the mechanics of lead circuits. Examine bipolar limb leads, electrical axis patterns, and the differences between lead axes and vectors. Study cardiac activity from various angles, including frontal and horizontal planes. Analyze lead positions, deflections, and QRS vectors. Discover Einthoven's Triangle, its background, and the application of Einthoven's Law. Practice interpreting QRS changes in different directions through multiple examples. Gain insights into the relationship between Leads I, II, and III, and explore the triaxial reference system for a thorough understanding of ECG interpretation in cardiology.