Classified information in the United Kingdom

Classified information in the United Kingdom is a system used to protect information from intentional or inadvertent release to unauthorised readers. The system is organised by the Cabinet Office and is implemented throughout central and local government and critical national infrastructure. The system is also used by private sector bodies that provide services to the public sector.

The current classification system, the Government Security Classifications Policy, replaced the old Government Protective Marking Scheme in 2014. Since classifications can last for 100 years many documents are still covered by the old scheme.