This iBook is targeted to medical students struggling to grasp the basic concepts surrounding the electrocardiogram. It outlines how electromagnetic force vectors form from the movement of ions throughout the myocardium. We will then explore the various electrical vectors created during one cardiac cycle and link them to the standard waves seen on an ECG trace. Once these concepts have been established, we will learn about why there are multiple leads in a standard ECG, and more importantly, how these vectors are displayed on these leads. The final section of this book will then focus on interpreting the ECG in clinical practice.