Naval Ranks

• Stemming from naval tradition, the Navy and the Coast Guard have their own line of ranks. O-1 through O-10 are respectively referred to as ensign, lieutenant junior grade, lieutenant, lieutenant commander, commander, captain, rear admiral lower half, rear admiral upper half, vice admiral and admiral. Cadets at the Naval Academy are called Midshipmen, though Midshipmen still may commission into the Marine Corps, which works in tandem with the Navy.
  
  

Army-based Ranks

• The Army, Marines and Air Force follow the traditional ground-based terminology for officer corps names. These services refer to their ranks, O-1 through O-10, as second lieutenant, first lieutenant, captain, major, lieutenant colonel, colonel, brigadier general, major general, lieutenant general and general. While there are numerous differences between military officer ranks, the largest factor of confusion may be the shift in lieutenant reference and the fact that captains here are O-3 in rank, but naval captains are O-6 in rank. The change is distinct in that naval captains command entire vessels or similarly-sized naval bases while Army, Marine and Air Force captains command company-sized elements of only a few hundred troops.
  
  

Responsibilities of Company-grade Officers

• Company-grade officers in the military are composed of the first three ranks, O-1 through O-3. All lieutenants, ensigns and ground- and air-based captains are company-grade officers. Company-grade officers are tasked first with becoming proficient officers before anything else. This involves basic leadership schooling, followed by specialized training to match their particular area of military responsibility. After initial schooling, company-grade officers take control of the most basic levels of military organization, such as platoons or flights. Here they get the most hands-on leadership experience they will have in their careers as officers.
  
  

Responsibilities of Field-grade Officers

• Ranks O-4 through O-6 comprise the ranks of field-grade officers. These include all majors, lieutenant colonels, colonels, lieutenant commanders, commanders and naval captains. Junior field-grade officers typically fill higher positions of senior leadership, fill in for staff roles in strategic command or attend schooling to further advance their understanding of military leadership. Senior field-grade officers may command large units of troops, such as ships or regiments, or attend advanced schooling.
  
  

Responsibilities of Flag Officers

• Flag officers make up the general officers and the admiralty of the military's officer corps. These officers are responsible for overall strategic leadership and planning for the military. They also command units with troops numbering in the tens of thousands.