The lungs are the main organ of the respiratory system and diseases of the lungs are also respiratory diseases. Lung diseases include the following diseases. First, infectious diseases of the lung, including acute upper respiratory tract infection, acute tracheobronchitis, acute fine bronchitis, community-acquired pneumonia, hospital-acquired pneumonia, lung abscess, pulmonary fungal disease, pulmonary parasitic disease, tuberculosis and nontuberculous mycobacterial lung disease, and lung infection after bone marrow and organ transplantation. Second, tracheal and bronchial diseases, including chronic cough, upper airway obstruction, bronchial asthma, chronic obstructive pulmonary disease, bronchiectasis, pulmonary atelectasis, diffuse panbronchitis, occlusive fine bronchitis, tracheal and bronchial foreign bodies. Third, pulmonary vascular disease, including pulmonary thromboembolism, pulmonary vasculitis, pulmonary arteriovenous fistula and pulmonary vascular malformation, pulmonary hypertension, and pulmonary heart disease. Fourth, bronchial and lung tumors, including bronchial lung cancer, bronchial and benign lung tumors, and metastatic lung tumors. Fifth, idiopathic interstitial pneumonia and other diffuse lung diseases. The above is the general classification of lung diseases, lung disease infection is the focus, including the lung parenchyma and interstitial lung, in addition to the immune system diseases in the lung manifestations are gradually increasing, need to give sufficient attention.