An electrocardiogram (EKG) technician records and interprets electrocardiograms. Electrocardiograms record the electric activity of the heart. These readings are used in a number of ways. Primarily they help doctors determine the health of a patient's heart and heart rate. EKG's are also used to diagnose heart disease. Technicians often learn on the job as licensing or training are often not required. Training programs do exist and are usually offered through trade schools and community colleges.