The military ranks indicate a Soldier's authority and standing.
In the Army the ranks go from an E1 to an E9.
E1: Private
E2: Private 2
E3: Private First Class
E4: Specialist/Corporal
E5: Sergeant
E6: Staff Sergeant
E7: Sergeant First Class
E8: First Sergeant/Master Sergeant
E9: Sergeant Major/Command Sergeant Major/Sergeant Major of the Army
Promotion to the next higher rank for enlisted is usually based on length of service in the grade they hold, satisfactory performance of their duties, and a vacancy in the next higher grade.
Enlisted personnel are paid according to their rank and length of service.
Increases are added to minimum basic pay after certain years of service are completed.