Pulmonary medicine integrates detailed physiologic understanding with careful clinical assessment to diagnose and manage respiratory disease. This first volume emphasizes history-taking, physical exam techniques, pulmonary function testing, gas-exchange physiology, and common infectious lung diseases. It explains ventilatory mechanics and the pathophysiology behind cough, dyspnea, hypoxemia, and respiratory failure to inform diagnostic reasoning. Infectious pathologies—pneumonia, bronchiectasis, atypical infections, and TB—are presented with practical diagnostic algorithms and treatment principles. Imaging interpretation, sputum and bronchoscopy sampling, and bedside decision tools are woven into clinical chapters. Useful for students, trainees, and clinicians who want physiology-driven pulmonary practice.