When searching for screws, nuts, washers, retaining rings, or dowel pins, you may encounter a long list of standards: DIN, ISO, JIS, ANSI, ASTM, CNS, GB, BS, AS…Why are there so many? What’s the difference? How do you choose the correct one? This article breaks down the origins, differences, and real-world uses of global fastener standards in a clear and easy-to-understand way. --- 1. Why Do We Need Fastener Standards? Fasteners are mating parts —screws match nuts, washers ma