Sergeant (normally abbreviated to "Sgt") is a rank used in some form by most militaries, police forces, and other uniformed organizations around the world. Its origins are the Latin serviens, "one who serves", through the French term Sergent.

In most armies[clarification needed] the rank of sergeant corresponds to command of a squad (or section). In Commonwealth armies it is a more senior rank, corresponding roughly to a platoon second-in-command. In the United States Army sergeant is a more junior rank, corresponding to a squad second-in-command.

More senior non-commissioned ranks are often variations on sergeant, for instance staff sergeant, sergeant first class, master sergeant, first sergeant and sergeant major. The spelling serjeant is used in a few regiments of the British Army.