In military organizations, a commissioned officer is a member of the service who derives authority directly from a sovereign power, and as such holds a commission from that power. Commissioned officers are authorized to use deadly force to carry out the lawful orders of their government, either directly or through orders to enlisted personnel.
Commissioned officers usually study military science at a college, university or military academy and intend to make a career in the military. In contrast, non-commissioned tend to receive much less training and education before they are put to work and often leave the military after the end of their initial term of commitment. In many countries in the past (and in some still today) most non-commissioned personnel were conscripts, whereas most officers were volunteers.
Officers and enlisted personnel are highly segregated: for example, they typically eat their meals and spend their off-duty time in separate facilities.
There is sometimes a third grade of personnel, small in number, called warrant officers. Some warrant officers are commissioned though.
Having officers is one requirement for combatant status under the laws of war, though these officers need not be commissioned.
In the United States, there are some uniformed commissioned officers who are not members of the military. See uniformed services of the United States, NOAA Corps, and United States Public Health Service.
British and American commissioned officer ranks
Many of the militaries of the world base their officer ranks upon the officer ranks of the British and American militaries. Officer ranks are typically differently titled but equivalent in rank between the army and navy. For more information, see Comparative military ranks.
British Commissioned Officer Ranks
The highest rank currently held by a Royal Marines officer is Lieutenant-General, although the rank of General still exists. The position of Captain-General, which is currently held by the Duke of Edinburgh, is an office similar to that of Colonel-in-Chief, and is not a rank, although the insignia is that of a Field Marshal.
Royal Air Force
US commissioned officer ranks
Army / Air Force / Marine Corps
Navy / Coast Guard