To begin, there are ten levels of officer rank in the United States Army. (An eleventh rank level is possible, but rare in military history.) Rank begins with the Second Lieutenant, and ends with the General of the Army. Along with each proper rank name, is an abbreviated rank identifier and an officer grade, or pay grade. The officer grades also start at O1 and end at O10.

It is easy to distinguish officers, who wear 'brass' on their collars, from enlisted soldiers, who wear 'stripes'. From bottom to top, the Army rank structure is as follows:

Second Lieutenant, 2LT, O1 - This is the lowest rank for the general-type officer. A soldier becomes a 2LT either through the ROTC program, attendance at a US Military Academy, or direct appointment. The 2LT wears a single gold bar on his collar, hence the nickname of 'butter bar' for these inexperienced officers. The grades of O1-O3 are known as 'company grade officers'.

First Lieutenant, 1LT, O2 - The First Lieutenant wears one silver bar on his collar. Usually, First Lieutenant's will serve as Platoon Leaders or Company Executive Officers. Advancement to First Lieutenant occurs after completion of 24-month time in grade as a 2LT.

Captain, CPT, O3 - The Captain wears two silver bars, side-by-side on his collar. The bars are referred to as 'railroad tracks' because of their visual similarity. Captains are generally assigned as Company Commanders, though they may also serve in a number of capacities, such as Logistics or Personnel Officers.

Major, MAJ, O4 - The Major wears the insignia of a gold oak leaf on his collar. Duty positions vary, though a Major could be assigned as a Battalion Executive Officer, Operations Officer, or Intelligence Officer. The grades of O4-O6 are known as 'field grade officers'.

Lieutenant Colonel, LTC, O5 - The Lieutenant Colonel wears the insignia of a silver oak leaf on his collar. Known as a 'light Colonel', the LTC is generally in command of a battalion sized unit.

Colonel, COL, O6 - The Colonel wears a silver eagle on his collar. The wearer of such rank is often referred to as a 'full bird' or, less often, a 'full bull'. Generally, a Colonel is in charge of a Brigade sized unit.

Brigadier General, BG, O7 - The Brigadier General wears one star on his collar. Brigadier's are usually positioned as Assistant Division Commanders. The grades of O7 and higher are known as 'general grade officers'.

Major General, MG, O8 - The Major General wears two stars on his collar. The duty position is generally that of a Division Commander, Post Commander, or any number of Commandant, Deputy Chief or Chief positions.

Lieutenant General, LTG, O9 - The Lieutenant General wears three stars on his collar. LTGs might fill a duty position such as a Deputy Commander of a major command, like Northern Command.

General, GEN, O10 - The General wears fours stars, side-by-side, on his collar. Four-star's occupy major command billets like Central Command, or might serve as a Chief-of-Staff.

General of the Army, GOA, O11 - This special rank consists of five stars in a pentagonal pattern, with star points touching. No officer has held this rank since World War II, when Omar Bradley was promoted to the position. By regulation, any officer holding the position of General of the Army will remain on active duty for life. Dwight Eisenhower, who also held this position, resigned his Army commission so that he might serve as President of the United States, because the office of President can not legally be filled by any active duty U.S. military officer.

General of the Armies, GOA, O11 - The General of the Armies is the highest ranking officer position in the military. Though it is sometimes considered a 'sixth star' rank, the insignia of the General of the Armies is the same five-star formation as that of the General of the Army. Promotion to this rank places the service member as the overall commander of all United States forces. This special rank and position has only been authorized for two people in our nation's history: George Washington and John J. Pershing. (By executive order of President Gerald Ford, George Washington will always remain the most senior commander, and can never be outranked by any other officer of the U.S. military.)

Each of the aforementioned ranks is special in its own way, and holds a valuable place in the military hierarchy. Though their ranks, duties and responsibilities may vary, soldiers serving at every level of the military order are equally as important as their fellow service members.