Cardiopulmonary resuscitation (CPR) is a life-saving technique involving chest compressions and ventilations for patients in cardiac arrest. It is crucial to position the patient correctly on a hard surface, perform compressions at a rate of 100 to 120/min, and provide rescue breaths if trained. The document also discusses the indications, contraindications, and steps to take before beginning CPR, emphasizing the importance of a safe environment and calling emergency services.