Fever is actually not the name of a disease, it is actually the name of a symptom itself. In clinical work, we often encounter patients who ask, if they have pneumonia, is it a fever that becomes pneumonia, or if they have a cold, is it a fever that becomes a cold, but in fact it is not. Because fever itself is a symptom, it is caused by pneumonia or because of the cold, because of the disease he got, not fever caused by these diseases. Fever can be divided into low fever, medium fever, high fever and ultra-high fever according to the increase in body temperature. Generally speaking, we say that a body temperature above 39°C is a relatively high body temperature, which should be paid special attention to, which may cause functional damage to the organs of the body, especially for children. Children’s febrile convulsions, we may have more or less heard of, so we have to control the temperature within a relatively safe range, we generally think that 38 ℃, 38.5 ℃ below the body temperature is relatively safe body temperature, will not cause irreversible damage to the organs. Then there is the classification of fever, which can also be classified according to the course of its illness. There are some fevers that are acute, with a sudden onset, accompanied by some other symptoms, and with reasonable treatment, his temperature will be normalized, which is acute. There are also some diseases that cause chronic fever, the patient may have a longer fever, or he may have repeated fevers over a period of time, these are to be particularly important, a disease diagnosis of a piece of information that we have to provide to the doctor, so that the doctor can help us, based on these conditions, to determine the cause of the disease, what the cause of the fever is, and better find the cause of the disease. Also, special attention should be paid to the fever type. The so-called fever type is whether we have a fever in the morning or at night, once or twice a day, or a continuous increase in body temperature throughout the day, and the causes of each fever type are different. Therefore, if you have fever, you should pay special attention to your fever, when it started, how long each fever lasts, whether the antipyretic medicine can bring down the temperature, and whether you have chills before the fever. Especially in children, fever is not a minor problem. If you find a fever, please go to the hospital for medical treatment in time, otherwise it is unthinkable.