Moff designated the political standing of the governors overseeing each sector within the Galactic Empire. Galactic Emperor Sheev Palpatine established a group known as the Council of Moffs. Moffs also served as military officers. Consequently, as the Imperial Senate's influence waned and that power shifted to Moffs, the Empire evolved into a stratocracy.
During the fifth year of Emperor Sheev Palpatine's rule, there was a set number of twenty Moffs, all of whom reported to the Imperial Ruling Council. In that same year, the superior title of Grand Moff was introduced and given to Wilhuff Tarkin. Around that time, Palpatine also formed the Council of Moffs. As a symbol of their position, Moffs wore a rank insignia plaque featuring ten colored squares: five blue above three red and two gold, or twelve squares: six blue above three red and three gold. Moffs were authorized to use four code cylinders, carrying two in each pocket.
Moffs had control over their sector's Sector Group, a unit comprising resources from the Imperial Military and intelligence agencies. The Emperor or an advisor could appoint Moffs, but they were required to answer to both. A Grand Moff, who oversaw an oversector, had the authority to overrule any Moff. Following the Battle of Endor, Moff Valco Pandion declared himself a Grand Moff and attempted to gather his own fleet. Later, during the New Republic Era, Gideon commanded a significant Imperial remnant while holding the title of moff.
In Star Wars: Episode VI Return of the Jedi, Moff Jerjerrod mistakenly wore the rank plaque of a commander due to a wardrobe oversight. The specific rank badge for Moffs was initially shown in an illustration by Joe Corroney for Tarkin Revealed, an article by Michael Kogge that appeared in Star Wars Insider 153.