Cardiopulmonary resuscitation (CPR) is a lifesaving technique used in emergencies when someone's breathing or heartbeat has stopped. It involves a combination of chest compressions and rescue breaths to help maintain blood flow and oxygen to vital organs until professional medical help arrives. CPR can be performed by anyone, regardless of training, but knowing the correct technique increases its effectiveness. The process typically includes pushing hard and fast in the center of the chest and providing breaths if trained to do so. Early CPR can significantly improve the chances of survival in cases of cardiac arrest.