Cholesterol is a fatlike substance that's found in the cells of the body, according to the National Heart, Lung and Blood Institute and WebMD. It is needed by the body to form the membranes of cells and manufacture vitamin D, certain hormones and other materials needed for good health.
The body produces its own cholesterol, mainly in the liver, according to WebMD. People also get cholesterol from the foods they eat. Foods that contain cholesterol are almost exclusively from animals, says the American Heart Association, so cholesterol is found in eggs, fish, poultry, red meat and whole-milk dairy products.
Cholesterol can't dissolve in the blood and needs to be carried around the body by molecules called lipoproteins, according to the National Heart, Lung and Blood Institute. There are basically three kinds of these lipoproteins, according to WebMD. There is very low-density lipoprotein, low-density lipoprotein and high-density lipoprotein.
Low-density lipoprotein is considered the "bad" type because it is responsible for laying cholesterol on the walls of the arteries, claims WebMD. This is why high levels of this type of lipoprotein put a person at risk for hypertension and cardiovascular disease. On the other hand, high-density lipoproteins return excess cholesterol to the liver, which removes it from the body. Very low-density proteins carry triglycerides, which are also types of fat.