Electrocardiography (ECG or EKG) is a medical test that records the electrical activity of the heart over a period of time. It involves placing small electrodes on the skin, which detect electrical signals produced by heartbeats. These signals are then displayed as waves on a monitor or printed on paper, allowing healthcare professionals to assess the heart's rhythm, size, and overall health. ECGs are commonly used to diagnose various heart conditions, such as arrhythmias, heart attacks, and heart disease. The test is non-invasive, quick, and painless, making it a valuable tool in both emergency and routine medical settings.