This document summarizes NIST Special Publication 800-53 Revision 4 which provides a catalog of security and privacy controls for federal information systems and organizations. It describes how organizations can select controls to protect operations, assets, individuals and organizations from threats. The controls are customizable and implemented as part of an organization-wide risk management process. It also describes how specialized control overlays can be developed for specific environments. Finally, it addresses both security functionality and assurance to ensure systems are sufficiently trustworthy.