This book Lung is written for the primary care clinician to help update the knowledge of pediatric pulmonology (pulmo, pulmonis [Latin for "lung"] and , -logia [Greek for "study of"]) in the early 21st century. It acknowledges some of the amazing stepping stones of science over time concerning the current understanding of pediatric pulmonary medicine. The current and future shortage of pediatric pulmonologists necessitates steady, rejuvenated information on asthma, cystic fibrosis, pneumonia and other pulmonologic disorders for primary care clinicians as they care for the children and adolescents with complex respiratory dilemmas and disorders. In view of this shortage and the rapidly increasing knowledge in this field, as well as understanding indications for referral to pediatric pulmonologists in the early 21st century, au courant assiduous information aimed at primary care clinicians in these areas becomes increasingly important.