A defibrillator is a medical device used to restore a normal heartbeat in someone experiencing a life-threatening heart rhythm problem, such as cardiac arrest. It delivers an electric shock to the heart, which can help reset its rhythm. There are different types of defibrillators, including automated external defibrillators (AEDs) that are often found in public places, making them accessible for emergencies. Using a defibrillator is straightforward. The device provides clear voice instructions, guiding users through the process. By following these steps, even untrained bystanders can help save a life until professional medical help, like paramedics, arrives.