After determining that a person is not breathing, the rescuer looks in the mouth and throat for any visible objects that may be blocking the airway and, if any are present, removes them. If the person does not start breathing, the tongue may be blocking the airway. The rescuer then tilts the person's head back slightly and lifts the chin, moving the tongue and thus opening the airway. If the person still does not start breathing, the rescuer begins artificial respiration. Opening the airway may be done as part of cardiopulmonary resuscitation (CPR).