Cardiopulmonary resuscitation (CPR) is a lifesaving intervention that can be used when someone’s heart stops beating. Performing CPR requires delivering high-quality chest compressions and ventilations to maintain good blood circulation. Being able to perform high-quality compression and recognize signs like pulselessness and unconsciousness are important steps to improve a person’s chances of survival. Some of these cases can be caused by arrhythmias like ventricular tachycardia or fibrillation, in which case an automatic external defibrillator can be lifesaving, as it terminates an abnormal rhythm. This chapter dives into the ABCs of CPR and emphasizes the importance of CPR training for everyone.