Before stormtrooper armor was developed, the first stormtroopers used Phase II clone trooper armor after the transition from the Republic to the Empire. It is unknown how long this was the case, but the Battle of Naboo in 18 BBY featured stormtroopers. If this is the case, they may have been in the Phase II armor for a few months before a transition to the later, distinct, and developed stormtrooper armor.
During the first years of the Empire, the Stormtrooper Corps, still composed of only Jango Fett clones, were forced to remove the color designs on their armor, used to designate legion or corps affiliation, to which the clones had worn with pride while serving under the old Jedi Order. This was due to the new Imperial protocol of uniformity. Thus, the first stormtroopers returned to their previous appearance of stark-white armored soldiers. This tradition would carry on into the new stormtrooper armor, and to the armor of the Legacy era as well.
Stormtroopers were the elite shock troopers of the Galactic Empire. Like Imperial-class Star Destroyers and TIE Fighters, stormtroopers served as ever present reminders of the Emperor's power, extensions of his will, and a method of keeping the Empire's thousands of star systems in line through fear.
Members of the Rebel Alliance SpecForce had several terms for stormtroopers, including whitehats, plastic soldiers, and snowmen. Another slang term for stormtroopers was the "Boys in White". Also, another was "Stormies", and was used often by Wedge Antilles and Corran Horn।