Cholesterol is the primary sterol in mammals, accounting for approximately 20–25% of the plasma membrane structure. It plays a key role in regulating membrane fluidity, permeability, and protein function. As an endogenous agonist of estrogen-related receptor α (ERRα), cholesterol is widely involved in metabolic regulation and serves as a precursor for the synthesis of hormones and bile acids. It is commonly used in experimental models of hyperlipidemia.