Fatty liver is a disease caused by lipid metabolic disorder and lipid accumulation in liver cells. If the fat accounts for more than 5% of the liver's total mass, it is defined as fatty liver, which is divided into three stages: mild fatty liver, moderate fatty liver, and severe fatty liver. Mild fatty liver is when the fat content is more than 5% but less than 10%; moderate fatty liver is when it exceeds 10% but is less than 20%; severe fatty liver is when it exceeds 20%. We must pay sufficient attention to mild, moderate, and severe fatty liver.