Cholesterol is a sterol lipid essential for animal cell membrane fluidity and integrity, serving as a structural component that modulates permeability and phase transitions. It acts as a precursor for bile acids, steroid hormones including cortisol and sex hormones, and vitamin D. Synthesized endogenously in the liver or obtained from dietary animal products, it exists in free and esterified forms. Elevated levels contribute to atherosclerosis, but the compound itself is vital for physiological functions. In food science, it occurs in eggs, dairy, and meat, influencing texture and nutritional profiles. Its amphipathic nature allows interaction with phospholipids in bilayers.