The clone troopers were created ten years prior to the outbreak of the Clone Wars by the cloners on the planet Kamino at the behest of Jedi Master Sifo-Dyas, according to the Kaminoans. There is some debate on this point, however, as Sifo-Dyas was killed more than ten years before the beginning of the War.
The genetic template of the clone troopers was Jango Fett, one of, if not the most, feared bounty hunter in the Galaxy at that time, as well as one of the last surviving Mandalorians, an ancient warrior culture. The clone troopers were outfitted with armor styled after Fett's Mandalorian battle armor and armed with weapons and vehicles produced in secret by Kuat Drive Yards.
Clone troopers were grown with accelerated speed, nearly double that of a normal human,though this rate would slow at the biological age of 10. Clone Troopers continue to age faster than humans, giving them a much reduced lifespan. At the age of 10 they are flash-trained in their specific tasks. Their genetic code was altered to make them more docile and subject to military discipline, though some clone units such as the Advanced Recon Clone (ARC) Troopers and Republic Commandos were allowed to retain more of Jango's original personality such that they could more-directly draw on his guile and years of combat experience. It is also noted that while some of the clones do possess a few human emotions including remorse and humor there is little that they can do if an order is given.
The Battle of Geonosis marked the first deployment of the clone troopers as well as the beginning of the Clone Wars. Beginning with the rescue of the remnants of Mace Windu's Jedi strike team, the clone army fought the Separatist forces on the rocky surface of Geonosis, forcing their retreat. Following that battle, the clone troopers were spread throughout the galaxy to engage the Confederacy of Independent Systems.
Clone trooper armies were led by Jedi Generals, who were in turn accompanied by Clone Commanders. Many clone commanders were placed into the ARC Training Program and became ARC Commanders, allowed to add to their standard kit and specialize their armor as well as the armor of their soldiers. Most of the ARC Commanders also took names which replaced their numerical clone designations. Commander Cody, who served with Obi-Wan Kenobi throughout the war, Commander Gree, who served with Jedi Master Luminara Unduuli, Commander Bacarra, who served with Jedi Master Ki-Adi Mundi, and Commander Bly, who served with Jedi Knight Aayla Secura, were all some of the most accomplished and superb examples of the ARC Commander program.
The clone troopers would eventually carry out Order 66 at the behest of Chancellor Palpatine and turn on their Jedi Generals. This marked the end of the Clone Wars, as well as the death of the Old Republic and the birth of the Galactic Empire. It was at this time that the clone troopers became the Imperial Stormtrooper Corps.