Fatty liver is caused by the accumulation of lipids in liver cells exceeding 5% of the wet weight of the liver due to factors such as diseases or drugs. The lipid content in the liver of a normal person accounts for 2% to 4% of the wet weight of the liver, of which 2/3 are phospholipids. In addition, there are cholesterol and neutral fats, which mainly constitute the membranes of cell membranes and other organelles. Most fatty livers are caused by abnormally high triglyceride content. According to the fat content, fatty liver can be divided into three types: mild (5% to 10% fat), moderate (10% to 25% fat), and severe (25% to 50% or >30% fat). Fatty liver is a common clinical phenomenon, not an independent disease. Fatty liver is a reversible disease, and early diagnosis and timely treatment can often restore normalcy.