If you're alone and choking, call 9-1-1 immediately. Put your fist slightly above your navel, grasp it with your other hand, lean over a table/chair and thrust upwards and inwards.
If an obese or pregnant person is choking, perform the normal procedure except: While doing the Heimlich maneuver, position your hands a little bit higher (just above lowest ribs).
If an infant under 1 is choking, sit down and hold them face down (support the head with your hand, place head below the trunk), thump the infant gently on the back with the heel of your hand 5 times, turn the infant face up, and do 5 compressions on their chest. Repeat until the object has been dislodged. Begin infant CPR if they still don't breathe.
If the person is unconscious and choking, lower them to the ground, try to get object out (if you can't see it, don't try), and begin CPR.
What you'll need if some one is choking, and becomes unconscious:
A CPR mask, if the object becomes dislodged but they still aren't breathing.
Gloves, in order to get objects out of their mouth.
Remember, if you even need to stop someone from choking or perform CPR: Stay calm, and call 9-1-1 if you are nervous or unsure.