Cholesterol is a molecule that is found in animal cells and body fluids. Cholesterol is not found in plant sources. It is a type of lipid which is a fat or fat-like molecule. Cholesterol is a soft waxy substance. Cholesterol is a special type of lipid that is called a steroid. Steroids are lipids that have a special chemical structure. This structure is made of four rings of carbon atoms. Cholesterol is found especially in animal fats.
Other steroids include hormone steroids like cortisol, estrogen, and testosterone. In fact, all steroid hormones are made from changing the basic chemical structure of cholesterol. When scientists talk about making one molecule from changing simpler ones, they sometimes call it synthesis.
Hypercholesterolemia means that cholesterol level is too high in the blood. Cholesterol levels that are high are possible precursors to heart disease.