The International Union of Biochemists has developed an identification system to classify enzymes. Naming of enzymes involves a numerical classification, a long systematic name, and a short, easy-to-use name. For example, the enzyme that
catalyzes the conversion of lactose (milk sugar) to galactose and glucose is classified as EC 3.2.1.23, has the systematic name β-D-galactoside galactohydrolase, and the common name lactase.