”Hepatitis” is the abbreviation of liver inflammation, which refers to inflammatory changes in the liver caused by viruses, drugs, alcohol or abnormal metabolism, and is seen in almost all kinds of liver diseases. Depending on the cause, liver inflammatory diseases can be divided into viral hepatitis, autoimmune liver disease, drug-related liver disease, alcoholic liver disease, non-alcoholic fatty liver disease, etc. Epidemiological findings show that the incidence of different liver diseases varies from country to country and region to region, and while the incidence and mortality rates of viral hepatitis B and C have decreased, alcoholic liver disease and nonalcoholic fatty liver disease have increased to varying degrees. The etiology of common liver inflammatory diseases is described as follows: 1. Viral hepatitis: Inflammation due to infection with hepatitis viruses (hepatitis A, B, C, D, E, etc.). Hepatitis B virus (HBV) infection is a global epidemic, according to the World Health Organization reported that about 2 billion people worldwide have been infected with HBV, about 350 million people with chronic HBV infection. China has about 93 million people with chronic HBV infection and about 20 million people with chronic hepatitis B (CHB). About 1 million people worldwide die each year from liver failure, cirrhosis and primary hepatocellular carcinoma (HCC) caused by HBV infection. The global infection rate of hepatitis C virus (HCV) is about 2.35%, with about 160 million people chronically infected; past surveys in China found an HCV infection rate of about 3.2%, but a significant decline has been reported in recent years, for example, a 2006 study showed that the prevalence of anti-HCV in people aged 1 to 59 years was about 0.43%. The reason for the large difference between the two is unclear, and some experts believe that the actual prevalence rate may be around 1% at present. 2, drug-related (toxic) liver disease: liver damage due to drugs and hepatotoxic substances, including acetaminophen, anti-tuberculosis drugs (such as isoniazid, rifampin, pyrazinamide, etc.), antimetabolites, antitumor chemotherapy drugs, some herbal medicines, anti-rheumatic drugs, etc. In recent years, with the increase of drug types, the emergence of new drugs and the increased application of various drugs, the incidence of drug-induced liver damage has increased significantly. There are some differences in the proportion of DILI to liver disease at home and abroad, for example, DILI in the United States accounts for 2% to 5% of hospitalized liver disease patients, while China only accounts for 0.46% to 1.08%, which may be related to the relatively high rate of hepatitis virus infection in China and the relatively high proportion of viral hepatitis patients; on the other hand, in view of our medical system and other reasons, there may also be underestimation. 3, alcoholic liver disease: liver disease caused by long-term heavy drinking, the initial stage is usually manifested as fatty liver, which can then develop into alcoholic hepatitis, liver fibrosis and cirrhosis; severe alcohol abuse can induce extensive liver cell necrosis or even liver failure, related risk factors include obesity, viral infections, genetic factors, etc. According to the survey, 44% of all liver disease deaths in the United States in 2003 were attributed to alcohol. Studies have found that for every 1L increase in annual per capita alcohol consumption, the proportion of men with cirrhosis increases by 14% and women by 8%. In Europe, ALD is the most common cause of advanced liver disease. Our 1999 survey of six regions of the country showed that male, female and overall alcohol consumption rates were 84.1%, 29.3% and 59.4%, respectively. In our adult population, the prevalence of ALD is 4.3% to 6.5%. With the improvement of living standard of Chinese residents, the proportion of ALD in hospitalized patients with liver disease in the same period is increasing, from 4.2% in 1991 to 21.3% in 1996; the composition ratio of alcoholic cirrhosis in the cause of liver cirrhosis increased from 10.8% in 1999 to 24.0% in 2003. 4, non-alcoholic fatty liver disease: a metabolic stress liver injury closely related to insulin resistance and genetic susceptibility, its pathological changes are similar to ALD, but patients do not have a history of excessive alcohol consumption, and the disease spectrum includes non-alcoholic simple fatty liver, non-alcoholic steatohepatitis (NASH) and its associated cirrhosis and hepatocellular carcinoma. NAFLD is a common cause of liver function enzymatic abnormalities and chronic liver disease in developed countries such as Europe and the United States, and the prevalence of NAFLD in the general adult population ranges from 20% to 33%. the prevalence of adult NAFLD was 15.4% in the Shanghai Community Survey in 2004 and 35.1% in the Beijing Community Survey in 2011. Many risk factors for NAFLD, such as diabetes mellitus, hypertension and obesity, have led to a rapid increase in the prevalence of NAFLD in China, with a trend of lower age onset. Among NAFLD patients, NASH and cirrhosis accounted for 10%-20% and 2%-3%, respectively. The prevalence of NAFLD in obese patients is 60% to 90%, NASH is 20% to 25%, and cirrhosis is 2% to 8%. The incidence of cirrhosis in NASH patients has been reported to be as high as 15% to 25% within 10 to 15 years. Two studies showed that 61.5% and 64% of patients with non-alcoholic simple fatty liver disease developed NASH after 3 years and 3.7 years of liver penetration respectively. 5, autoimmune liver disease: with a group of liver diseases due to autoimmune abnormalities, the prominent feature is the presence of autoantibodies in the serum including autoimmune hepatitis (AIH), primary biliary cirrhosis, primary sclerosing cholangitis and other autoimmune diseases liver involvement. The prevalence of AIH is 1/5000 to 1/10000 in western developed countries and is more common in women (male to female ratio 1:3.6). Although AIH can occur in people of any age, it mainly affects children and middle-aged and elderly patients. In Norway and Sweden, the average incidence of AIH is 1 to 2 cases per 100,000 people per year, and the incidence of AIH in North America is similar. autoimmune liver diseases other than AIH include PBC, PSC and its overlapping syndromes, whose incidence in China has shown a significant increase in trend, which is due to the clinical awareness, and the second is indeed a rising trend itself. 6, other: many chemical toxins can cause liver damage, the occurrence of toxic hepatitis, such as arsenic and mercury, carbon tetrachloride, etc.. The degree of damage to the liver depends on the time of exposure to chemical toxins dose, as well as individual quality differences. Long-term use or repeated exposure can lead to chronic hepatitis and even cirrhosis. Many other systemic infectious diseases can invade the liver, such as EBV, cytomegalovirus, typhoid fever or Schistosoma chinensis, which can cause elevated serum transaminases or other liver function abnormalities. However, because each of these diseases has its own specific manifestations, liver inflammation is only one part of the disease manifestation. In conclusion, multiple lines of evidence suggest that liver inflammation is seen in almost all causes of liver disease. The current large number of patients with liver inflammation from various causes in China is still dominated by viral hepatitis, but the incidence (detection rate) of drug-related liver disease, alcoholic and non-alcoholic fatty liver disease, and autoimmune liver disease is on the rise.