What are NATO four levels of classified information?

NATO classifies information into four levels: Unclassified, Restricted, Confidential, and Secret. Unclassified information is open to the public, while Restricted requires limited access to protect operational effectiveness. Confidential information is more sensitive, necessitating protection to prevent damage to NATO interests, and Secret information is highly sensitive, where unauthorized disclosure could cause serious harm to NATO's security. Each level has specific handling and access protocols to safeguard the information accordingly.