Cholesterol is a soft, fat-like, waxy substance found in the bloodstream and in all your body's cells. It's normal to have cholesterol and it's an important part of a healthy body because it is used for producing cell membranes and some hormones. It also serves other needed bodily functions. But too much cholesterol in the blood is a major risk for coronary heart disease (which leads to heart attack) and for stroke. Hypercholesterolaemia is the medical term for high levels of blood cholesterol.