Non-commissioned officer
A non-commissioned officer (NCO) is a military officer who has not earned a commission. Non-commissioned officers usually obtain their position of authority by promotion through the enlisted ranks (Non-officers, which includes most or all enlisted personnel, are of lower rank than any officer.) In contrast, commissioned officers usually enter directly from a military academy, Officer Candidate School (OCS), or Officer Training School (OTS) after receiving a post-secondary degree.