Cholesterol is a substance found almost exclusively in animal cells, rarely in plant cells, and almost devoid of prokaryiotic cells. It is an organic substance that has natural applications within animal eukaryotic cells. Cholesterol is classified as a waxy steroid of fat. It is synthesized naturally within an animals body, primarily by organs, such as the liver. Cholesterol is also available from the foods we eat, primarily those associated with living animal cells, such as poultry, pork, beef, and eggs. Cholesterol is used in the manufacture of bile and bile acids; bile is used to help break down fatty substances in the intestines into simpler forms so they may be used by the body. Cholesterol is also used to manufacture steroid hormones, such as testosterone in males and estrogen and progesterone in females. Cholesterol is also used to manufacture and produce important vitamins, such as vitamin D. A synthesis of cholesterol by the body may be found in the attached resource under the "Biosynthesis" section.