Sergeant (Sgt) is a rank in use by the armed forces of many countries. It is also a police rank in some police services. The alternative spelling, serjeant, is used in The Rifles and other units that draw their heritage from the British light infantry. Its origin is the Latin serviens, 'one who serves', through the Old French term serjant.

In military terminology, a squad is among the smallest of military organizations and is led by a non-commissioned officer. NATO and U.S. doctrine define a squad as an organization "larger than a team, but smaller than a section." while U.S. Army doctrine further defines a squad as a "small military unit typically containing two or more fire teams." In American usage, a squad consists of eight to fourteen soldiers, and may be further subdivided into fireteams.