It is wrong to think that fever causes pneumonia, as fever is only one symptom of pneumonia. The source of pneumonia, also known as the cause of pneumonia, is mainly infectious, physicochemical, and immune metabolic reactions, etc. Among the physicochemical, immune, and metabolic pneumonia, the medical history is generally clear and can be maintained with medication. However, the vast majority of common clinical pneumonias are infections caused by various microorganisms that cause pneumonia, where the pathogens include bacteria, viruses, chlamydia, mycoplasma, rickettsia, and parasites, among others. Pneumonia is an acute inflammation of the lung and is a common clinical infection that can be classified anatomically as lobar pneumonia, lobar pneumonia and interstitial pneumonia. In recent years, due to the widespread use of antibiotics, mild pneumonia or atypical pneumonia is very common in clinical practice.