A dependency relationship is a record in software inventory data, such as an SBOM, that shows one component relies on another. For example, an application may depend on a logging library, which in turn depends on a parser or crypto package. This relationship is important because software is rarely built from a single codebase; it is assembled from layers of reusable components, build tools, and third-party libraries.
In cyber security, dependency relationships help teams trace exposure quickly. If a vulnerable library is discovered, defenders can see which products inherit that risk through direct or transitive dependencies and prioritize patching or compensating controls. Attackers also target dependencies, especially in supply-chain attacks, because compromising one upstream package can affect many downstream applications. Accurate relationship data improves vulnerability matching, software validation, and procurement review, but it only works when the SBOM is complete and machine-readable.