During life ECG is always changing according to postnatal circulation adaptation, position of the heart in the chest, and body mass. Reference values and normal morphologies of P wave, PR interval, QRS complex, ST segment, T wave, and QTc interval are reported. Some clues to detect congenital and acquired heart diseases are also provided. Finally, a brief look at the most common diseases and arrhythmias in the neonatal and pediatric period is reported. When the pediatric ECG is too "young" for a cardiologist? When we need to stop doing the report? ... never! The baby is the father of the adult. The heart is made of signs: we have to decipher them.