This chapter discusses the general market status of nylon resins, the system used to identify the nylon types, and the basic synthetic methods used to produce the major and minor types. The advantages and limitations of nylon resins as engineering materials and the comparative properties of the nylon types are discussed. The interpretations of some major properties are described, and tabulations are given on the properties of nylons 6, 616, 6/10, 6/12, I I,and 12.