Cholesterol is not a fat. Cholesterol is widely found in the body of animals, especially in brain and nerve tissues where it is more abundant, and in other organs, like liver, kidney, spleen, as well as in skin and bile, where it is relatively high. The solubility of cholesterol is relatively similar to that of fat, insoluble in water and soluble in solvents such as ether and chloroform. Cholesterol is an essential substance for animal tissues and cells, participating in the formation of cell membranes and synthesizing bile acids, vitamin D and some steroid hormones. Cholesterol is metabolized by the body and can be converted into bile acids and steroid hormones, so it is not a harmful substance. Cholesterol is an important indicator of clinical biochemical examination. Under normal conditions, the cholesterol synthesized by the organism in the liver and taken from food is converted into steroid hormones or becomes a component of cell membranes, and the concentration of cholesterol in the blood is kept constant. In case of serious pathology of the liver, the cholesterol concentration will decrease.