This book serves as the primary reference for precision medicine in the fields of pulmonary, critical care and sleep medicine by documenting principles written by experts in several aspects of precision medicine. It combines fundamental concepts of the field with state-of-the-art studies and how they translate into individual preventive, diagnostic and therapeutic plans. Precision medicine is focused on the integration of individual variability with disease prevention and treatment principles derived from population studies. This concept has risen to prominence in recent years in parallel with advances in genetics, molecular diagnostics and novel target-specific therapies. This fundamental shift in the approach to treatment has broad implications in how we prevent, diagnose and treat disease.