During a typical electrocardiogram (ECG or EKG), atrial depolarization is represented by the **P-wave**. The P-wave shows the electrical activity as the atria (the upper chambers of the heart) contract and send electrical signals to the ventricles (the lower chambers of the heart) to initiate the heartbeat. It's an important component of the ECG that helps in diagnosing various cardiac conditions and assessing the overall heart rhythm.