Systems thinking is an approach that studies how parts of a project interact, not just each part on its own. In cyber security, that means looking at users, devices, software, networks, policies, and supply chains as one connected environment. A weakness in any single layer can affect the rest, so defenders use systems thinking to spot dependencies, bottlenecks, and hidden failure points before attackers do.
Attackers often exploit these relationships rather than one isolated bug. For example, phishing may succeed because identity controls, training, and email filtering do not work together well enough. Defenders apply systems thinking through layered controls, segmentation, logging, change management, and incident response planning. It helps organizations build resilience by making security part of the overall design, not an afterthought.