Cholesterol is a substance that your liver produces naturally. It’s vital for the formation of cell membranes, vitamin D, and certain hormones.
Cholesterol is a waxy, fat-like substance. It doesn’t dissolve in water and therefore can't travel through the blood by itself. Lipoproteins are other particles formed in the liver that help transport cholesterol through the bloodstream. There are several major forms of lipoproteins that are important to your health.
Source: quickanddirtytips