Final answer:
An electrocardiogram (ECG) is a recording of the electrical changes in the myocardium, which is the muscular tissue of the heart. It is a diagnostic tool used to measure the electrical activity of the heart and identify abnormalities.
Step-by-step explanation:
An electrocardiogram (ECG) is a recording of the electrical changes in the myocardium, which is the muscular tissue of the heart. It is a diagnostic tool used to measure the electrical activity of the heart and identify abnormalities. The ECG is obtained by placing electrodes on the chest that detect and record the voltage changes associated with the wave of depolarization and repolarization in the heart.