The Secret Intelligence Service (SIS), commonly known as MI6 (Military Intelligence, Section 6) is the Unite Kingdom's external intelligence agency. Under the direction of the Joint Intelligence Committee (JIC), it works alongside the Security Service (MI5), Government Communications Headquarters (GCHQ) and the Defence Intelligence Staff (DIS). Within the civil service community the service is colloquially referred to as 'Box 850' which comes from its old post office box number.