Commander

Commander is a naval rank. It may also be used as a general term for a leader.  Numerous law enforcement agencies in the United States have personnel who are in charge of running their entire operations.  Commander is a rank used in many navies and some air forces. It is rarely used as a rank in armies, except in special forces for a team leader. 

 Naval rank   

The title (originally "Master and Commander") originated in the 18th century Royal Navy for naval officers who commanded ships of war too large to be commanded by a Lieutenant but too small to warrant the assignment of a Post-captain.Post-captains were formally appointed as Captains, whereas anyone commanding a naval vessel was addressed by the courtesy title of 'captain'. 

In practice, these were usually unrated sloops-of-war of no more than 20 guns. The Royal Navy shortened "Master and Commander" to "Commander" in 1794; however, the term "Master and Commander" remained in common use for many years.Naval Historical Center: Why is the Colonel called a 'Kernal?'|url=http://www.history.navy.mil/trivia/triv4-5h.htm|year=1998 A corresponding rank in some navies is frigate captain. In the 20th and 21st centuries, the rank has been assigned the NATO rank code of OF-4.

A Commander in the Royal Navy is above the rank of Lieutenant-Commander, below the rank of Captain. It is equivalent in rank to a Lieutenant Colonel in the British Army and Wing Commander in the Royal Air Force. A Commander may command a frigate, destroyer, submarine, aviation squadron or shore installation, or may serve on a staff.

 Related pages 
Commander-in-Chief
Captain
Lieutenant

 References 

Category:Military ranks
Category:Royal Navy