PDCA stands for Plan-Do-Check-Act, a simple cycle for continuous improvement. In cybersecurity, it is used to build, test, measure, and refine controls rather than treating security as a one-time project. Teams plan a control or policy, do the implementation, check the results with logs, audits, or incident metrics, and act by fixing weaknesses or standardizing what works.
This cycle matters because threats change quickly. A phishing filter, backup process, or access policy can look effective on paper but fail in practice. PDCA helps defenders detect that gap early and improve steadily. In real security programs, it appears in vulnerability management, incident response, patching, awareness training, and compliance reviews. Attackers benefit when organizations skip the checking step, because untested controls often leave predictable openings.