Pneumonia is an acute infectious disease of the respiratory tract that occurs in the alveoli. The main symptoms of pneumonia are, first, fever; second, significant malaise, which means that the patient is in a particularly weak state; and third, cough, sputum, and even hemoptysis. In general, the main difference between pneumonia and bronchitis is that fever and weakness are very obvious in pneumonia, but cough and sputum are relatively mild or even absent, so it should be different from bronchitis. In some patients with severe pneumonia, the patient may even experience respiratory distress and even respiratory failure as well as important damage to multiple systems and organs, such as heart failure, kidney failure, and other organ functions. The main diagnosis is based on the detection of large solid and exudative lung lobes on chest radiographs or CT. The prognosis for most pneumonias is relatively good, and the most common bacterial pneumonias, such as Streptococcus pneumoniae pneumonia, can be cured in almost 90% or more of cases. Some pathogens cause pneumonia, such as viral pneumonia, especially some highly contagious viruses, such as SARS virus caused by viral pneumonia, including some rare influenza virus pneumonia, the prognosis is relatively poor, the patient is easy to develop acute respiratory failure, or even death.