The acronym FOUO refers to For Official Use Only.
The FOUO designation is meant to alert personnel on how to store, transmit and share the information securely. Unauthorized disclosure of FOUO could adversely affect government operations or an individual’s privacy.
FOUO materials:
While FOUO still exists within the US Government, FOUO is being phased out with Controlled Unclassified Information (CUI) designations as a more granular way to label information that is sensitive but not classified.