Cholesterol, from stereos (solid) and the Greek chole- (bile) followed by the chemical suffix -ol for an alcohol is an organic chemical substance classified as a waxy steroid of fat. It is an necessary structural element of mammalian cell membranes and is requires to built proper fluidity and membrane permeability

Additionally to its significance within cells and cholesterol also serves as a precursor for the biosynthesis of bile acids and steroid hormones and vitamin D. That is the principal sterol synthesized by animals; in vertebrates it is establish predominantly in the liver. Little quantities are synthesized in other cellular organisms (eukaryotes) such as fungi and plants. It is almost completely absent among prokaryotes like bacteria.