Well, we basically take special electrodes and we connect the electrodes onto the surface of the skin as special locations on the body. So six electrodes are usually placed around the heart. Two electrodes are placed on the arms and two electrodes are placed on the legs. And that creates a closed electric circuit. And if we connect the wires to a special device, that device can read the electrical signal that is generated by our heart. So we basically create an electrocardiogram that is nothing more than an XY graph, where the X axis is the time and the Y axis is the voltage.