Millions of individual parts, assemblies, and materials circulate throughout the U.S. government’s defense networks, so if only proprietary naming conventions were used, stocking and sourcing activities would be chaotic and fragmented across different branches. To keep products easy to locate and manage, the Department of Defense relies on the National Stock Number (NSN) system and its sub-classifications to create a shared language. This blog will specifically explore the role of Federal Supply Groups (FSGs) and Federal Supply Classes (FSCs), cluing you into how these identifiers contribute to a carefully organized supply chain for defense item classification.