Taurine, or aminoethane sulfonic acid, is an organic compound which is widely distributed in animal tissues. It is a chief constituent of bile and is typically found in the large intestine. It also accounts for up to 0.1% of total human body weight. Taurine has many important biological roles, such as membrane stabilization, antioxidation, conjugation of bile acids, osmoregulation, and modulation of calcium signaling. It is vital for cardiovascular function, the growth and function of the retina, the central nervous system, and for skeletal muscle. Taurine is unusual amid biological molecules in that it is a sulfonic acid while the vast majority of biologically occurring acids contain the weaker acidic carboxyl group. While taurine is called an amino acid at times, and certainly is an acid containing an amino group, it is not an amino acid in the traditional biochemical meaning of the term - which denotes to compounds containing both a carboxyl and amino group.