Military officers are the leaders of the military, and instead of enlisting in the sense that enlisted military men and women do, they are commissioned officers who serve indefinitely at the pleasure of the President of the United States. We should note that the officer ranks also include Warrant Officers (CWO2 through CWO5) who must have served 13 enlisted service years prior to commissioning, and are specialists and experts in certain military technologies or capabilities.
Air Force
The Air Force ranks share the same titles as the Army and Marines.
Company Grade Officers (O-1 through O-3): The junior grades of officers in the Air Force often serve as more administrative leaders, though O-3s may be given authority over a company (becoming a "Company Commander").
Pay Grades: Second Lieutenant (O-1), First Lieutenant (O-2), Captain (O-3)
Field Grade Officers (O-4 through O-6): With continued areas of responsibility and sizes of commands, Field Grade Officers final rank of O-6 may command elements of a wing, while others serve as heads of staff in Air Force staff agencies.
Pay Grades: Major (O-4), Lieutenant Colonel (O-5), Colonel (O-6)
Generals: The O-8 is a two-star general and is the highest rank an Airman can achieve during peacetime. Ranks above this are picked by the president, temporary, and removed when they end their terms. The maximum number of four-star Generals allowed in the Air Force at a given time is nine.
Pay Grades: Brigadier General (O-7), Major General (O-8), Lieutenant General (O-9), General (O-10)
Army
The Army ranks are the same as the Air Force and Marines, except that, unlike the Air Force, the Army has a five-star "General of the Army."
Company Grade Officers (O-1 through O-3): The junior grades of officers in the Army control progressively more troops, from generally 16 to 44 soldiers for an O-1, to company-sized units of 62 to 190 soldiers for an O-3.
Pay Grades: Second Lieutenant (O-1), First Lieutenant (O-2), Captain (O-3)
Field Grade Officers (O-4 through O-6): The numbers of soldiers led at these rank increase to brigade-sized units for O-6 (up to 5,000 soldiers).
Pay Grades: Major (O-4), Lieutenant Colonel (O-5), Colonel (O-6)
Generals: Generals in the Army start as Deputy Commander to the commanding generals for Army divisions. The Chief of Staff of the Army is a four-star General. A five-star general, or General of the Army, is only used in time of war.
Pay Grades: Brigadier General (O-7), Major General (O-8), Lieutenant General (O-9), General (O-10).
Coast Guard
Coast Guard officer pay grades are the same as the Navy.
Company Grade Officers (O-1 through O-4): The approximate time it takes to go from O-1 to O-2 is 18 months. O-2s serve as billeted division officers, while O-3s are responsible for sailors and petty officers in different divisions. O-4s usually operate as mid-ranking officers in executive and command divisions
Pay Grades: Ensign (O-1), Lieutenant, Junior Grade (O-2), Lieutenant (O-3), Lieutenant Commander (O-4)
Field Grade Officers (O-5 through O-6): O-5s are the first Coast Guard rank to command ships or squadrons of aircraft. O-6s are given a high degree of autonomy in a variety of stations.
Pay Grades: Commander (O-5), Captain (O-6)
Admirals (O-7 through O-9): O-7s generally command small flotillas of ships, while O-8s command fleets of ships and air wings and are the highest Coast Guard rank during peacetime. O-10 Admirals are the highest rank in the Coast Guard, and reports directly to the president.
Pay Grades: Rear Admiral Lower Half (O-7), Rear Admiral Upper Half (O-8), Vice Admiral (O-9), and Admiral (O-10).
Marine Corps
Marine Corps pay grades for officers have ranks similar to the Army and Air Force.
Company Grade Officers (O-1 through O-4): O-2 is generally automatic after two years as an O-1. O-3s act as Company Commanders for 62 to 190 Marines, and are in charge of the tactical and everyday operations of their company.
Pay Grades: Second Lieutenant (O-1), First Lieutenant (O-2), Captain (O-3)
Field Grade Officers (O-5 through O-6): To achieve O-5 takes approximately 16 to 22 years time-in-service. They command between 300 and 1,000 Marines. O-6s typically attend the Army War College.
Pay Grades: Major (O-4), Lieutenant Colonel (O-5), Colonel (O-6)
Generals: Generals in the Marine Corps start off by presiding over 10,000 to 15,000 Marines, and are in charge of tactical planning and coordination of operations. Three-star generals (O-9) can only extend their status through an act of Congress. There may only be 60 total generals in the Marine Corps, and 3 of those can be four-star generals.
Pay Grades: Brigadier General (O-7), Major General (O-8), Lieutenant General (O-9), General (O-10).
Navy
The Navy rank structure is similar to the Coast Guard.
Company Grade Officers (O-1 through O-4): O-1s and O-2s are often in schools for training, or serving in the fleet as Division Officers. O-2 generally comes after two years' time-in-service (TIS). O-3s are often Division Officers or service heads on some smaller ships, in aircraft squadrons, submarines, and ships. O-4's serve as Department Heads or Executive Officers on a ship, aircraft squadron, or submarine.
Pay Grades: Ensign (O-1), Lieutenant, Junior Grade (O-2), Lieutenant (O-3), Lieutenant Commander (O-4)
Field Grade Officers (O-5 through O-6): As Senior Officers, O-5s may command a Frigate, Destroyer, Fast Attack Submarine, Smaller Amphibious Ship, Aviation Squadron, SEAL Team, or shore installation. O-6's serves as Commanding Officers of Major Commands such as Aircraft Carriers, Amphibious Assault Ships, Cruisers, Destroyer Squadrons, Carrier Air Wings, Ballistic Missile Submarines, Submarine Squadrons, SEAL Groups and major shore installations.
Pay Grades: Commander (O-5), Captain (O-6)
Admirals (O-7 through O-9): The Admiral ranks (also known as flag officers) are at the same level as Generals in the other services, and in the Navy command various ships and groups from an Amphibious Group, Carrier-Cruiser Group, to numbered fleets for O-9s. Assignments for Admirals (O-10) include Commanders of Regional Commands, Joint Commands, Chief of Naval Operations, and Chairman of the Joint Chiefs of Staff.
Pay Grades: Rear Admiral Lower Half (O-7), Rear Admiral Upper Half (O-8), Vice Admiral (O-9), and Admiral (O-10).
More details on Navy officers are available on Military.com.
