Idiopathic pulmonary fibrosis (IPF) is also known as idiopathic fibrosing alveolitis, Hamman-Rich syndrome, idiopathic diffuse interstitial fibrosis of the lung, and European scholars call it cryptogenic fibrosing alveolitis. It is now often referred to as fibrosing alveolitis (FA). It is a diffuse progressive pulmonary interstitial fibrosis of unknown cause. It may not be a disease, but only the terminal stage of chronic interstitial pneumonia caused by various reasons. It is more common in adults, but can also occur in infants and children. Clinically, it is characterized by irritating dry cough, shortness of breath, progressive dyspnea and hypoxemia. The condition often continues to progress and eventually leads to death from respiratory failure.