1) CPR is performed to move blood to the heart and brain through chest compressions and provide oxygen through rescue breaths when someone suffers cardiac arrest or their heart stops beating. 2) CPR procedures vary based on the age of the victim, being either adult, child, or infant. It involves checking for responsiveness, calling for emergency help, providing chest compressions and rescue breaths in a repeated cycle until emergency services arrive or the victim shows signs of life. 3) For a choking victim, back blows are used for adults and children while chest compressions are used for infants to dislodge any blockages in the airway. CPR is started if the person becomes unresponsive during choking treatment.