Final answer:
An EKG records the electrical activity of the heart via skin electrodes, focusing on the voltages from depolarization and repolarization waves.
Step-by-step explanation:
An EKG records the voltages of electrical activity of the heart via skin electrodes. The process involves placing electrodes on the body to capture the wave of depolarization and repolarization that occurs as the heart beats. State-of-the-art ECG machines can have 12 or more leads to provide a detailed picture of heart function, identifying regions of damaged tissue and monitoring heart health over time. The voltage between two electrodes, such as the right arm and the left leg (lead II potential), is most commonly used to assess heart muscle function.