There is no clear distinction between the stages of pneumonia per se, but pneumonia can be divided into the following categories based on the clinical characteristics of the patient: 1. The inflammatory infection period, when the patient’s immunity decreases after exposure to cold, exertion, alcohol and other disease triggers, and there may be no obvious clinical symptoms. 2. The patient develops a series of symptomatic manifestations, which can be called the onset period. 3. The patient’s clinical symptoms improve significantly, and the lung imaging lesions are significantly absorbed, which can be called the clinical recovery period.