Army Troop Organization

Squad -- The smallest military unit, it usually consists of 10 to 11 soldiers.

Platoon -- A platoon is usually four squads. Platoons are usually led by lieutenants, with sergeants serving as their second-in-command.

Company -- Companies consist of four platoons, a headquarters and some logistical staff. They are normally commanded by captains.

Battalion -- A battalion is usually made up of four to five companies, including a support company and a headquarters company.

Brigade -- A brigade is a collection of battalions, usually 2,000 to 3,000 troops. Brigades are most often commanded by a colonel.

Division -- There are at least three brigades in a division. They are usually commanded by a major general.

Corps -- Made up of two to five divisions, corps are the largest tactical units in the U.S. Army.

Marine Organization

The Marine Corps, a branch of the Navy, has some unit classifications that are unique.

Marine Expeditionary Force -- An expeditionary force is made up of two or three divisions of Marines. The force is usually deployed on helicopter carriers or amphibious assault ships. Its equipment and weaponry includes tanks, artillery, Harrier jump jets and attack helicopters.

Marine Expeditionary Unit -- Each marine division is known separately as a Marine Expeditionary Unit. The unit usually includes a battalion landing team, helicopter squadron and support unit.

Military Slang And Jargon

APC -- Armored personnel carrier, a tanklike vehicle that carries troops

BDUs -- Battle Dress Uniforms, what soldiers and marines wear on the battlefield

CO -- Commanding Officer

Frag, Fragging -- To murder a fellow soldier. From 'fragmentation grenade.'

GPS -- Global Positioning System. A satellite triangulated 'compass' that gives the GPS's location

Humvee -- High Mobility Multi-purpose Wheeled Vehicle, the military's current version of the Jeep. Also called a 'hummer.'

Kevlar -- Protective material capable of stopping small caliber bullets and shrapnel. Troops wear Kevlar vests with a ceramic front plate capable of stopping larger caliber rifle rounds. Military helmets are also lined with Kevlar.

LZ -- Landing zone, where troops are deposited by helicopter or land after parachuting from a plane.

MRE -- Meals Ready to Eat, packaged food carried by troops for their own consumption.

NBC -- Nuclear, Biological, Chemical. Often used to describe equipment and training related to those battlefield threats.

NCO -- Non-Commissioned Officer, usually refers to sergeants.

OPSEC -- Operational Security.

POW -- Prisoner Of War.

PsyOps -- Psychological Operations. The production and distribution of media in native languages with the intent of informing the locals of American actions, desires and views, usually with the hope of producing a desired action.

RPG -- Rocket-Propelled Grenade.

SAW -- Squad Automatic Weapon, a light machine gun

SOP -- Standard Operating Precedure

TOW -- A heavy antitank missile. Its name is derived from its description as a Tube-launched, Optically tracked, Wire-guided missile.

XO -- Executive Officer. The second-highest ranking soldier in a unit.

Enlisted Rank
Army	Navy	Marines	Air Force
Private	Seaman Recruit	Private	Airman Basic
Private E-2	Seaman Apprentice	Private First Class	Airman
Private First Class	Seaman	Lance Corporal	Airman First Class
Corporal | Specialist	Petty Officer Third Class	Corporal	Senior Airman
Sergeant	Petty Officer Second Class	Sergeant	Staff Sergeant
Staff Sergeant	Petty Officer First Class	Staff Sergeant	Technical Sergeant
Sergeant First Class	Chief Petty Officer	Gunnery Sergeant	Master Sergeant | First Sergeant
Master Sergeant | First Sergeant	Senior Chief Petty Officer	Master Sergeant | First Sergeant	Senior Master Sergeant | First Sergeant
Sergeant Major	Master Chief Petty Officer	Sergeant Major	Chief Master Sergeant
Warrant Officer	Warrant Officer (no longer in use)	Warrant Officer	N/A
Chief Warrant Officer	Chief Warrant Officer	Chief Warrant Officer	N/A
Second Lieutenant	Ensign	Second Lieutenant	Second Lieutenant
First Lieutenant	Lieutenant Junior Grade	First Lieutenant	First Lieutenant
Captain	Lieutenant	Captain	Captain
Major	Lieutenant Commander	Major	Major
Lieutenant Colonel	Commander	Lieutenant Colonel	Lieutenant Colonel
Colonel	Captain	Colonel	Colonel
Brigadier General	Rear AdmiralLower Half	Brigadier General	Brigadier General
Major General	Rear Admiral Upper Half	Major General	Major General
Lieutenant General	Vice Admiral	Lieutenant General	Lieutenant General
General	Admiral	General	General