Respiratory diseases are a group of diseases that affect the lungs and other parts of the human respiratory system. These diseases can be classified into three types, namely, airway diseases, lung tissue disease and lung circulation diseases. The main cause of respiratory diseases is air pollution, smoking tobacco, or breathing asbestos and radon. Airway diseases are conditions that affect airways carrying oxygen and other gases into and out of the lungs. Some common airway diseases are bronchiectasis, asthma and chronic obstructive pulmonary disease (COPD). Asthma is a major chronic respiratory disease that causes difficulty in breathing. Some common symptoms of asthma include wheezing, coughing and tightness in the chest. The diseases that affect the structure of the lung tissue are called lung tissue diseases. They are caused by scarring or inflammation of the tissues which restrict the lungs from expanding properly. This book is a practical guide to respiratory diseases. It includes some of the vital pieces of work being conducted across the world, on various topics related to these diseases. This book includes contributions of experts and doctors which will provide innovative insights into respiratory diseases.