This chapter is structured as a historical overview of the history of the development of defibrillators and the most prominent personalities who contributed to the development of the modern concept of resuscitation. Defibrillators in medical practice can be external or implanted. The devices, known as automated external defibrillators, automate the diagnosis of a patient’s rhythm and the process of stopping arrhythmias, meaning they can be used successfully by nonspecialists. In Europe, 350,000–700,000 people suffer from sudden cardiac arrest every year. On average, it is 55–113 per 100,000 people. Most of these people are usually at home, but about 10–20% of victims are in a public place at the time. Defibrillation within 3–5 minutes of cardiac arrest can increase survival by 50–70%. For every minute that defibrillation is delayed, the chance of survival decreases by 10–12%. A significant contribution to the development of the defibrillation concept was made by Peter Kristians Abildgård, Albert Salisbury Hyman, William Bennett Couwenhoven, Paul Morris Zoll, James Francis Pantridge, and many others. Clinical studies confirm that public access defibrillators (PADs), when available and used correctly during out-of-hospital cardiac arrest, were associated with a 40% median survival rate.