A chief petty officer is a senior non-commissioned officer in many navies and coast guards.
"Chief petty officer" refers to two ranks in the Royal Canadian Navy. A chief petty officer 2nd class (CPO2) (premier maître de deuxième classe or pm2 in French) is equivalent to a master warrant officer in the Army and Air Force, and chief petty officer 1st class (CPO1) (premier maître de première classe or pm1) is equivalent to a chief warrant officer in the Army and Air Force. In spoken references, chief petty officers may be addressed as "chief" but are never addressed as "sir".
"Chief Petty Officer" is the second highest non-commissioned rank in the Royal Australian Navy.
Fleet chief petty officer is a commissioned and gazetted rank in Pakistan Navy above chief petty officer and below master chief petty officer. It is equivalent to the Pakistan Air Force warrant officer and the Pakistan Army subedar.
In the Royal Navy, the rank of chief petty officer comes above that of petty officer and below that of warrant officer class 2, which is being phased out. It is the equivalent of colour sergeant in the Royal Marines, colour sergeant or staff sergeant in the Army, and flight sergeant in the Royal Air Force.
Chief petty officer is the seventh enlisted rank in the U.S. Navy and U.S. Coast Guard, just above petty officer first class and below senior chief petty officer. Chief petty officers are classified as senior non-commissioned officers. The grade of chief petty officer was established on April 1, 1893 for the U.S. Navy. The U.S. Congress first authorized the U.S. Coast Guard to use the promotion to chief petty officer on 18 May 1920.
Unlike petty officer first class and lower rates, advancement to chief petty officer in the U.S. Navy not only carries requirements of time in service, superior evaluation scores, and specialty examinations, but also carries an added requirement of peer review. A chief petty officer can only advance after review by a selection board of serving master chief petty officers, in effect "choosing their own" and conversely not choosing others.
...commemorating the establishment of the rate of Chief Petty Officer (CPO) in 1893.