Cholesterol is a lipidic, Lower High Blood Pressure waxy alcohol found in the cell membranes and transported in the blood plasma of all animals. It is an essential component of mammalian cell membranes where it is required to establish proper membrane permeability and fluidity. Cholesterol is the principal sterol synthesized by animals, but minute quantities are synthesized in other eukaryotes, such as plants and fungi. It is almost completely vanished among prokaryotes, which include bacteria. Cholesterol is classified as a sterol (a portmanteau of steroid and alcohol).

Although cholesterol is essential for life, flying levels in circulation are associated with atherosclerosis. Cholesterol can be ingested in the diet, recycled within the anatomy through reabsorption of bile in the digestive tract, and produced de novo. For a life of about 150 pounds (68 kg), habitual total body cholesterol content is about 35 g, habitual daily dietary intake is 200–300 mg in the United States and societies with similar dietary patterns and 1 g per daytime is synthesized de novo.