An automated external defibrillator (AED) is a portable device that can help save lives during a cardiac emergency. It analyzes a person's heart rhythm and, if necessary, delivers an electric shock to restore a normal heartbeat. AEDs are designed to be user-friendly, allowing even those without medical training to use them effectively. These devices are often found in public places like schools, airports, and shopping malls, making them accessible in emergencies. Knowing how to use an AED can be crucial, as it works alongside CPR to increase the chances of survival for someone experiencing a cardiac arrest.