An electrocardiogram (EKG or ECG for short) records the electrical activity of your heart. An EKG provides information about your heart's rate and rhythm, and diagnoses a variety of heart conditions. To perform an EKG, sensing electrodes are placed on the skin of your chest, arms, and legs. The electrodes are small adhesive patches with wires that connect to a monitor. The monitor captures and displays your heart's electrical activity. The number of electrodes worn during an EKG depends on the kind of information healthcare providers want to capture.