Final answer:
An AED is a life-saving device used to treat cardiac arrest by applying an electrical shock to restore the heart's normal rhythm, commonly found in public places and often accompanied by desired CPR treatment.
Step-by-step explanation:
An automated external defibrillator (AED) is a portable device that is used to treat sudden cardiac arrest. It is designed to diagnose cardiac arrhythmias of ventricular fibrillation and pulseless ventricular tachycardia, and to treat them through defibrillation, the application of electricity which stops the arrhythmia, allowing the heart to reestablish an effective rhythm. AEDs are essential tools found in ambulances and are also available in many public places, providing clear verbal instructions for easy use by the general public. When someone experiences cardiac arrest, signified by sudden collapse, unresponsiveness, and not breathing or only gasping, prompt application of an AED, accompanied by cardiopulmonary resuscitation (CPR), can greatly increase the chance of survival.