EKG and ECG stand for electrocardiogram, which is a test that evaluates the electrical activity of the heart, according to WebMD. The electrical activity is transmitted onto paper in the form of waves. These line tracings are called spikes and dips.
According to Mayo Clinic, the EKG is a pain-free test that usually returns results to the doctor within the same day. WebMD reports that an EKG is performed for many reasons, including finding the cause of heart disease, determining how medication affects the heart, observing how devices are working and checking the health of the heart when other illnesses are present.