Fatty liver refers to a pathological condition characterized by the accumulation of excessive fat in liver cells, caused by various factors and marked by diffuse fatty changes in liver cells, constituting a clinical syndrome. When too much fat accumulates inside liver cells, it impairs normal liver function, a condition we refer to as fatty liver. The main causes include long-term diets high in fats, calories, and sugars leading to obesity-induced fatty liver, chronic alcohol consumption leading to alcoholic fatty liver, and hereditary obesity factors causing fatty liver. Based on the extent of fatty degeneration in liver cells, fatty liver can be classified into mild, moderate, and severe fatty liver. Fatty liver could potentially lead to liver cirrhosis, which may cause liver cancer. Upon diagnosis of fatty liver, dietary control, abstaining from alcohol, and active exercise are necessary for treatment.