Fibrosis is refers to the excessive matrix deposition that results in the impairment of organ function and tissue destruction. It is the end result of chronic inflammatory responses brought on by a variety of stimuli such as autoimmune responses, tissue damage, persistent infections, allergic reactions and radiation. The fibrosis of lung tissue is known as pulmonary fibrosis. Some of its prominent symptoms are fatigue, shortness of breath, aches in joints and muscles, and clubbed toes or fingers. It can lead to a variety of medical complications such as respiratory failure, pulmonary hypertension, lung cancer, and other lung complications. There are various tests which can be used to diagnose pulmonary fibrosis. These include pulse oximetry, echocardiogram, chest X-ray, and pulmonary function testing. This book is compiled in such a manner, that it will provide in-depth knowledge about pulmonary fibrosis. It aims to shed light on some of the unexplored aspects of this disease. A number of latest researches have been included to keep the readers up-to-date with the global concepts in this medical condition.