(1) Concept Hepatitis is a variety of inflammation of hepatocytes caused by pathogenic microorganisms, such as parasites, viruses, toxins and drugs, as well as autoimmune factors. It is characterized by degeneration, lysis, necrosis and regeneration of hepatocytes. Since the liver is the center of material metabolism in the human body and an important organ for maintaining life, its functional state is related to the health of the human body, so any disease occurring in the liver has a very great impact on the human body. (2) Classification Hepatitis is divided into viral hepatitis, alcoholic hepatitis, drug-related hepatitis, toxic hepatitis, autoimmune hepatitis, non-alcoholic steatohepatitis, etc. Viral hepatitis: It is a group of systemic infectious diseases caused by a variety of hepatitis viruses, mainly liver inflammation and necrotic lesions. According to the pathogenesis can be divided into seven types of A, B, C, D, E, H, G, of which hepatitis B is the most widespread and harmful one. Other viruses such as EBV, cytomegalovirus, herpes simplex virus, rubella virus, etc. can also cause hepatitis, but each has its own clinical characteristics and are not included in this scope. Alcoholic hepatitis: It is a form of alcoholic liver disease, which is an inflammatory lesion of the liver caused by long-term heavy consumption of various ethanol-containing beverages. According to domestic clinical standards, alcoholic liver disease or alcoholic liver occurs in most alcoholics who drink more than 80 grams of alcohol per day for more than 5 consecutive years. Drug-related hepatitis: It is an inflammatory liver lesion caused by drugs or/and their metabolites. Certain drugs such as chlorpromazine, sulfonamide, para-aminosalicylic acid, isoniazid, etc. can result during clinical treatment. Since the liver plays an important role in drug metabolism, it is one of the main target cells for adverse reactions. Toxic hepatitis: inflammatory lesions of the liver caused by physical, chemical, biological and other hepatophilic toxicants in the natural environment (e.g. phosphorus, arsenic, carbon tetrachloride, etc.). Autoimmune hepatitis: a group of inflammatory liver lesions of unknown etiology characterized by hyperglobulinemia, multiple autoantibodies and debris-like necrosis in the confluent area. Its onset is mostly insidious and slow, and the disease is mostly hereditary. Non-alcoholic steatohepatitis: a clinical-pathological syndrome of hepatic steatosis and associated necroinflammatory changes, which can be diagnosed only by liver biopsy. The hepatic histological changes are similar to those of alcoholic hepatitis, but without a history of excessive alcohol consumption.