The Tarkin Doctrine was a policy instituted by the Galactic Empire to maintain order and increase security. It is named after its creator, Grand Moff Tarkin.
The Tarkin Doctrine originated from a message that then Moff Tarkin sent to Emperor Palpatine. Also known as the Doctrine of Fear or officially Imperial Communiqué #001044.92v, the Tarkin Doctrine advocated the creation of Oversectors to handle Rebel activities in a group of system, using the Holonet to coordinate Sector Groups, and most infamously, using fear of force, rather than force itself, to maintain control. Finally, he suggested creating an overwhelmingly powerful weapon to impress and frighten the people, and cement Imperial authority through its sheer size and power. Emperor Palpatine was impressed by these ideas, and implemented all of them, promoting Tarkin to Grand Moff. The Death Star was created to be the symbol of the Tarkin Doctrine, a superweapon that could crush resistance and restore order simply by existing.
The Tarkin Doctrine was considered a failure, as the Empire was not able to instill the fear that would keep the systems in line. Even the destruction of the planet Alderaan was not able to suppress rebellion, and in fact brought sympathy and support to the Rebel cause. When the Death Star, the ultimate symbol of Imperial might and power, was destroyed, the Tarkin Doctrine died along with it.