Protecting Controlled Unclassified Information in Non-federal Information Systems and Organizations: The protection of Controlled Unclassified Information (CUI) while residing in non-federal information systems and organizations is of paramount importance to federal agencies and can directly impact the ability of the federal government to successfully carry out its designated missions and business operations. This NIST 800-171 Special Publication provides federal agencies with recommended requirements for protecting the confidentiality of CUI.