The Ministry for State Security (German: Ministerium für Staatssicherheit, MfS), commonly known as the Stasi ( ) (abbreviation German: Staatssicherheit, literally State Security), was the official state security service of the German Democratic Republic or GDR (informally known as East Germany). It has been described as one of the most effective and repressive intelligence and secret police agencies in the world. The Stasi was headquartered in East Berlin, with an extensive complex in Berlin-Lichtenberg and several smaller facilities throughout the city. The Stasi motto was "Schild und Schwert der Partei" (Shield and Sword of the Party), that is the ruling Socialist Unity Party of Germany (SED). It is now considered a criminal organisation, and several Stasi officials were prosecuted for their crimes after 1990.
Read more about Stasi: Creation, Relationship With The KGB, Organization, International Operations, Fall of The Soviet Union, Recovery of The Stasi Files, Museum in The Old Headquarters, Alleged Informants