Primary prevention is also called etiological prevention. It is the main task of primary prevention and the ultimate goal of preventive medicine to eliminate disease causing factors and prevent harm to human body by putting forward comprehensive preventive measures against biological, physical, chemical, psychological and social factors of disease occurrence. It means that for healthy people who do not have diseases, we can find out the possible disease-causing factors for your clothing, food, residence, transportation and family relationship, and provide guidance and prevention to avoid the occurrence of these diseases. SecondaryPrevention, also known as preclinical prevention, is a preventive measure for early detection, early diagnosis and early treatment when the disease is still in the preclinical stage. Secondary prevention measures include screening, regular medical checkups, and key monitoring of high-risk groups. Once these diseases occur, we will guide you on how to treat them and how to prevent them from developing into serious diseases. TertiaryPrevention, also known as clinical prevention, is to take timely and effective treatment measures to prevent the deterioration of the disease, prevent complications and sequelae, and to restore or preserve the function of those who have lost their working ability or disability through rehabilitation medical treatment. It is to cure the disease and prevent the disability, prolong life and improve the quality of life.