Stormtroopers are the primary infantry of the Galactic Empire in the Star Wars trilogy. They are immediately recognisable by their pure white armour and helmets and are the most common threat to the heroes of the Star Wars films. They are typically armed with blaster rifles.
While the stormtroopers are referred to as being the Empire's elite fighting force in the Star Wars Expanded Universe, they are shown to be rather incompetent in the films. They are described as being precise marksmen, yet they fail utterly to even wound most characters they fight against in the films. It is only in Return of the Jedi that any stormtroopers get a lucky shot in as both R2-D2 and Princess Leia are shot in the film, though not killed.
Decades after the Empire was defeated, the First Order arose from its ashes and initiated an extensive military campaign against the New Republic. To build up its forces, it abducted countless young humans from all over the galaxy and subjected them to rigorous mental conditioning to create obedient and skilled soldiers. These stormtroopers appeared similar to the original Imperial soldiers with only minor differences to the armour they wore, though they have proven to be somewhat more competent than their predecessors.