Classified information is material that a government body deems to be sensitive information that must be protected. Access is restricted by law or regulation to particular groups of people with the necessary security clearance and need to know, and intentional mishandling of the material can incur …
A typical classified document. Page 13 of a U.S. National Security Agency report on the USS Liberty incident, partially declassified and released to the public in July 2004. The original overall classification of the page, "top secret", and the Special Intelligence code word "umbra", are shown at top and bottom. The classification of individual paragraphs and reference titles is shown in parentheses—there are six different levels on this page alone. Notations with leader lines at top and bottom cite statutory authority for not declassifying certain sections.
KGB traitors list seen in Museum of Genocide Victims Vilnius: originally marked top secret
A building in Wuhan housing provincial offices for dealing with foreign countries etc. The red slogan says, "Protection of national secrets is a duty of every citizen".
KGB Regulation seen in Museum of Genocide Victims Vilnius