When you are thinking about installing a home defibrillator in your home and are wondering how an automatic defibrillator works, and whether it is worth your investment, then in this article we will go over the explanation of what is a defibrillator device, automatic electronic defibrillator device, and how a lay person can use it successfully to resuscitate a person experiencing a heart failure, and by doing so tremendously increase the chance of victim's survival.
What is a defibrillator, or an AED? A defibrillator is an electronic, or computerized device that

• measures, and records the heart beat information as the electrodes are pressed against the persons chest
• diagnoses the heart rate characteristics quickly
• administers an appropriate electric shock to the heart if the diagnosis warrants it

In addition to the above, the defibrillator will also permanently record the electric signals from the electrodes, as well as possibly the surrounding voices.
A defib machine will, upon being turned on, provide textual, and voice instructions on how to use it effectively.
Based on the instructions, even a person who has never been trained on proper use of AED, or CPR, or has never performed a CPR/AED resuscitation, can successfully operate a defibrillator and possibly save a heart patient's life.
How to use defibrillators successfully? To use a cardiac defibrillator with maximum success as a lay person, it is important to follow a "chain of survival".
This is a series of four steps that maximize the chances of survival of a heart attack victim, as has been shown in many instances.
Here are the four steps needed:

• Recognize the heart emergency and call 911 and make sure that emergency medical service, EMS, will be able to locate you.
  The heart emergency will usually result in a person's collapse, and their pulse will either be weak or non existing, or it will be rapid (yet ineffective in getting blood into brain)
• Perform hands only CPR on the person, by pressing on the center of the chest and depressing by about 2 inches.
  This is what American Heart Association recommends.
  If a defibrillator is not available, perform it until the EMS arrives.
  
• When a defibrillator is available, turn it on and follow the directions.
  For most AEDs it takes about a minute or so to diagnose the situation and administer an electric shock to the heart if appropriate.
  Continue with the CPR after AED.
  
• Offer advanced life support.
  There is nothing you can do here.
  This is the job of the emergency medical services as they arrive.
  

As you can see, the above steps in using automated external defibrillators are easy enough a layman can do them.
We still recommend to take CPR/AED training course to take the maximum advantage of a defibrillator in your home or place of business.