Non-commissioned officer

A non-commissioned officer (NCO) is an enlisted leader, petty officer, or in some cases warrant officer, who does not hold a commission. Non-commissioned officers usually earn their position of authority by promotion through the enlisted ranks.

In contrast, commissioned officers usually enter directly from a military academy, officer training corps (OTC) or Reserve Officers' Training Corps (ROTC), or officer candidate school (OCS) or officer training school (OTS), after receiving a post-secondary degree.

The NCO corps usually includes many grades of enlisted, corporal and sergeant; in some countries, warrant officers also carry out the duties of NCOs. The naval equivalent includes some or all grades of petty officer. There are different classes of non-commissioned officers, including junior (lower ranked) non-commissioned officers (JNCO) and senior/staff (higher ranked) non-commissioned officers (SNCO).

The non-commissioned officer corps has been referred to as "the backbone" of the armed services, as they are the primary and most visible leaders for most military personnel. Moreover, they are the leaders primarily responsible for executing a military organization's mission and for training military personnel so they are prepared to execute their missions. NCO training and education typically includes leadership and management as well as service-specific and combat training.

Senior NCOs are considered the primary link between enlisted personnel and the commissioned officers in a military organization. Their advice and guidance are considered particularly important for junior officers and in many cases to officers of all senior ranks.

In the Australian Army, lance corporals and corporals are classified as junior NCOs (JNCOs), sergeants and staff sergeants (currently being phased out) are classified as senior NCOs (SNCOs), while warrant officer class two and warrant officer class one are classified as warrant officers (WOs).

In the New South Wales Police Force, NCOs perform supervisory and coordination roles. The ranks of probationary constable through to leading senior constable are referred to as "constables". All NCOs within the NSW Police are given a warrant of appointment under the Commissioner's hand and seal.

All officers within the Australian Defence Force Cadets are non-commissioned, with ADFC officers appointed by the Director-General of their respective branch.