General Directorate for the Protection of State Secrets in the Press under the Council of Ministers of the USSR (Russian: ? ? ? ? ?) was the official censorship and state secret protection organ in the Soviet Union. The censorship agency was established in 1922 under the name "Main Administration for Literary and Publishing Affairs at the RSFSR Narkompros", abbreviated as Glavlit (?). The latter term was in semiofficial use until the dissolution of the Soviet Union.
Since the word "Glavlit" hints at "literature", the organization is often confused with Goskomizdat, which performed another type of censorship: it controlled the political content in fiction, poetry, etc.
The function of Glavlit was to prevent publications of information that could compromise state secrets in books, newspapers and other printed matter, as well as in radio and TV broadcasting.
There existed a special list of kinds of information forbidden for publication in sources open for general public. Initially there were three major categories of secret information: military, economical and "other". In later lists these were detailed further, e.g., "finance", "politics", "science and engineering", etc. were added. The first version of the list was decreed on October 13, 1921, before the creation of Glavlit, when censorship was a duty of a department of Vecheka. This list was updated several times. There were the following categories of secrecy: "top secret", "secret", and "not for disclosure".
In addition, for the purposes of the law the secrets were classified into "state secrets" (secrets related to the overall functioning of the state), "military secrets", and "official secrets" (secrets related to immediate functioning of an office or enterprise).
Glavlit performed its functions via regional offices. In the late Soviet Union, at institutions and enterprises the immediate censorship was performed by the so-called First Departments controlled by KGB. In fact, tight cooperation of Soviet secret services and Glavlit was unbroken from the very beginning.