Non-commissioned officer

A Non-commissioned officer, abbreviated to NCO and colloquially known as non-com or noncom, is a military officer who has not earned a commission. Such is also called sub-officer in some countries. Non-commissioned officers, in the English-speaking world, usually obtain their position of authority by promotion through the enlisted ranks. In contrast, commissioned officers hold higher ranks than NCOs, have more legal responsibilities, are paid more, and often have more non-military training such as a university diploma. Commissioned officers usually earn their commissions without having risen through the enlisted ranks.

In the British Armed Forces, NCOs are divided into two categories. Lance Corporals (including Lance Bombardiers) and Corporals (including Lance Sergeants, Bombardiers, and Lance Corporals of horse) are junior NCOs. Sergeants (including Corporals of Horse), Staff Sergeants (including Colour Sergeants and Staff Corporals), and RAF chief technicians and Flight Sergeants are senior NCOs.

Warrant officers (WOs) are often included in the senior NCO category, but actually form a separate class of their own, similar in many ways to NCOs but with a royal warrant. Senior NCOs and WOs have their own messes, which are similar to officers' messes (and are usually known as sergeants' messes), whereas junior NCOs live and eat with the unranked personnel, although they may have a separate Corporals' club to give them some separate socialising space. The Royal Navy does not refer to its petty officers and chief petty officers as NCOs, but calls them senior ratings (or senior rates). Leading ratings and below are junior ratings.