In the Star Wars prequels and the Clone Wars TV series, clone troopers are a mainstay of the events that take place during that time period in the Star Wars universe. Created by the cloning labs of Kamino from the DNA of notorious bounty hunter Jango Fett, the clone troopers form the military power of the Galactic Republic during the Clone Wars. They are placed under strict combat education during their growth and emerge from the Kaminoan clone factories as elite fighting machines. Unlike the robotic armies of the Confederacy of Independent Systems, clones are capable of thinking more creatively, making them superior fighters.
The clone troopers are the predecessors of the Stormtroopers employed following the Republic's reformation into the Galactic Empire. During the Galactic Civil War, the Empire built up its military primarily by recruiting humans from various planets into their stormtrooper ranks rather than relying solely on cloning. Eventually, Jango Fett's clones were phased out of the Imperial Army completely.
In virtually all of their appearances, clone troopers are shown to be killed in tremendous numbers. It is interesting to note that they are superior combatants to their stormtrooper successors in the original Star Wars trilogy.