This is a 40-year-old male, public employee, with mildly elevated liver function ALT (40-80 U/L) on annual unit physical examination for several years and ultrasound suggestive of fatty liver. We advised him to have a liver puncture, which resulted in steatosis in 80% of the liver cells, lobulitis, and ballooning of cells, which fully met the diagnostic criteria for steatohepatitis rather than simple fatty liver! Fatty liver, strictly speaking, is a pathological term that refers to steatosis of at least 5% of hepatocytes in the liver. The only way to accurately quantify the extent and size of hepatocellular steatosis is to diagnose it by liver aspiration pathology. However, the invasive nature of liver aspiration makes it difficult to generalize this test. Imaging examinations such as ultrasound, CT, and MRI can also reflect the distribution of liver fat, but still cannot replace liver pathology diagnosis. Non-alcoholic fatty liver disease (NAFLD) is divided into two subtypes: non-alcoholic fatty liver disease (NAFL) and non-alcoholic steatohepatitis (NASH). NAFL has a good prognosis in terms of liver histological progression, while NASH may progress histologically to fibrosis and up to 15% of patients may develop cirrhosis. In Western countries, 4% to 22% of hepatocellular carcinomas are caused by NAFLD. In addition, NASH has lobular and portal inflammation and hepatocellular ballooning liver injury that can progress to cirrhosis and hepatocellular carcinoma (HCC). It can be seen that non-alcoholic fatty liver (NAFL) and non-alcoholic steatohepatitis (NASH) have very different regressions, and the two states can be transformed into each other, but nowadays, routine liver function and ultrasound in hospitals do not distinguish between these two states. Therefore, the Fatty Liver and Alcoholic Liver Disease Group of the Chinese Medical Association Hepatology Section recommends liver biopsy pathology evaluation mainly for: (1) patients who have failed to make a definitive diagnosis despite routine examination and diagnostic treatment; (2) those who are at high risk of progressive liver fibrosis but lack clinical or imaging evidence of cirrhosis; (3) patients enrolled in drug clinical trials and diagnostic tests; (4) those who undergo laparoscopy for other purposes laparoscopy (e.g., cholecystectomy, gastric banding); (5) patients with a strong desire to understand the nature of liver disease and its prognosis.