Cholesterol, a lipid, is a waxy substance that forms all naturally occurring steroids such as sex hormones, bile acids, vitamin D, etc. synthesized by the body. It is a part of cell membranes, nerve linings, and other body components. Cholesterol is synthesized primarily in the liver. In fact, only about 1/4 to 1/2 of blood cholesterol actually comes from the food we eat.
Lipoproteins (fat and protein packages) bind with cholesterol and carry it through the blood. LDL (low-density lipoproteins) transports cholesterol from the site of synthesis to the area of use that can include arterial walls. HDL (high-density lipoproteins) removes cholesterol from the tissues and transports it back to the liver.