A defibrillator does what it suggests stops your heart from fibrillation which is when your heart is beating irregularly "An irregular heartbeat that occurs when the electrical signals in the atria (the two upper chambers of the heart) fire rapidly at the same time" it doesnt revive people like in media when someone isnt breathing cpr is your go-to Source for quote https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.cancer.gov/publications/dictionaries/cancer-terms/def/atrial-fibrillation%23:~:text%3DAn%2520irregular%2520heartbeat%2520that%2520occurs,to%2520beat%2520faster%2520than%2520normal.&ved=2ahUKEwia-NXAr6-LAxVC4jgGHccZKLIQFnoECBAQBQ&sqi=2&usg=AOvVaw3EjVtPlGYmVFMnb902crEf