Nylon 66 (aka nylon 6-6, nylon 6/6 or nylon 6,6) is a type of polyamide or nylon. Nylons come in many types, and the two most common for textile and plastics industries are nylon 6 and nylon 66. Nylon 66 is made of two monomers each containing 6 carbon atoms,  hexamethylenediamine and adipic acid, which give nylon 66 its name.