United States Military
Staff Sergeant insignia
(U.S. Air Force)
Staff Sergeant is the fifth enlisted rank in the U.S. Air Force, just above Senior Airman and below Technical Sergeant. It is the lowest form of non-commissioned officer.
Staff Sergeant insignia
(U.S. Army)
Staff Sergeant is the sixth enlisted rank in the U.S. Army, just above Sergeant and below Sergeant First Class, and is a non-commissioned officer. They are generally placed in charge of squads, but can also act as platoon sergeants in the absence of a Sergeant First Class.
Staff Sergeant insignia
(U.S. Marine Corps)
Staff Sergeant is the sixth enlisted rank in the U.S. Marine Corps, just above Sergeant and below Gunnery Sergeant, and is a non-commissioned officer.
British Army
Staff Sergeant (SSgt or S/Sgt) is also used in the British staff sergeants are never referred to as "Sergeant", which would be reducing their rank, but are referred to and addressed as "Staff Sergeant" or "Staff" ("Staff Jones", for instance) or by their appointment or its abbreviation. In some cavalry regiments (e.g. the Queen's Royal Lancers [1]), a staff sergeant is addressed as "Sergeant Major".