This Chief Information Officer, Secretary of the Navy (SECNAV) manual, SECNAV M-5239.3 Department of the Navy Cybersecurity Manual April 2022, describes key aspects of the Department of the Navy (DON) Cybersecurity (CS) Program. The DON CS Program must deliver secure, interoperable, and integrated information technology to the Marine, Sailor, civilian, and contracted workforce to support the full spectrum of DON enterprise, business, intelligence, warfighting, and warfighting support missions. Major elements of the program are to implement and enforce CS policies and procedures, ensure appropriate risk management, and require sustainment of an appropriate CS posture throughout the lifecycle of DON Information Technology (IT). This manual implements the policy set forth in reference (a) and is issued under the authority of reference (b). This manual is intended to serve as a high-level introduction to DON CS. It discusses common CS controls and associated DON and Department of Defense (DoD) requirements.