CPR is a life-saving first aid procedure when your heart stops or cannot maintain a proper rhythm (cardiac arrest). Otherwise known as cardiopulmonary resuscitation (CPR), it helps to keep blood flowing from the heart to other parts of the body. This meets the oxygen needs of the brain and other organs. It includes CPR, mouth-to-mouth breathing and chest compressions. However, as of 2010, the American Heart Association recommends that non-professionals focus on chest compressions only.

How to perform CPR is described in detail below:

1. Check Security: First, make sure the environment is safe. If the environment is not safe, both you and the patient may be at risk.
2. Check the Condition of the Victim: Check whether the victim is responsive. To do this, gently shake the person's shoulder and ask, “Are you OK?”.
3. Call for Help: If the person is unresponsive, call an ambulance immediately. Also, if possible, request an automated external defibrillator (AED).
4. Start Compressions: Lay the person on a hard, flat surface. Then place both hands in the center of the chest, just below the sternum (breastbone). Lock your elbows and, with strength from your shoulders, press the sternum down about 5-6 cm. Try to do these compressions at least 2 times per second (100-120 compressions per minute).
5. Exhalation (if trained): If you are trained in mouth-to-mouth breathing, give 2 breaths after every 30 chest compressions. However, this action requires training and can cause harm if done incorrectly.
6. Continue Reading: Continue this cycle until an ambulance arrives or a health professional takes your place.

CPR is a life-saving skill that everyone should learn. However, it requires training and practice to be done properly. For this reason, you may want to consider receiving training from Certified First Aid Trainers.