What is the rank structure in the us army?

Enlisted

E-1 = Private

E-2 = Private Second Class

E-3 = Private First Class

E-4 = Specialist/Corporal

E-5 = Sergeant

E-6 = Staff Sergeant

E-7 = Sergeant First Class

E-8 = Master Sergeant/First Sergeant

E-9 = Sergeant Major/Command Sergeant Major

Warrant Officer

WO1 = Warrant Officer 1

CW2 = Chief Warrant Officer 2

CW3 = Chief Warrant Officer 3

CW4 = Chief Warrant Officer 4

CW5 = Chief Warrant Officer 5

Officer

O-1 = Second Lieutenant

O-2 = First Lieutenant

O-3 = Captain

O-4 = Major

O-5 = Lieutenant Colonel

O-6 = Colonel

O-7 = Brigadier General

O-8 = Major General

O-9 = Lieutenant General

O-10 = General