Sergeant
Sergeant, an army, air force, or marine noncommissioned officer ranking above a corporal; also a police officer ranking above a patrolman but below a lieutenant. In the United States armed forces there are several grades of sergeants.
In the military, responsibilities and duties of sergeants vary according to a unit's function and the availability of sergeants. In general, sergeants in the lower grades have command over and train lower-ranking personnel while sergeants in the higher grades assist the officers in command. A first sergeant assists the company commander and sees that orders are carried out. Sergeants may also be technicians, holding such positions as communication specialist, computer operator, or maintenance-crew chief. Some sergeants have administrative positions, such as running a supply room or mess hall. A sergeant major is ordinarily the chief administrative assistant in a headquarters.
A sergeant of the guard is any enlisted person with the temporary assignment of supervising soldiers on guard duty.
A police sergeant supervises about eight officers and acts as a liaison between them and the higher-rank officers. Police sergeants have various jobs, including patrol duty and detective work. A desk sergeant is in charge of the receiving desk in a police station.