A hard drive (or hard disk drive, HDD) was the main data storage device of many primitive computers.
Earth computers of the late 20th century and early 21st century used magnetic hard drives as their principal storage device. Such drives were susceptible to disruption by 24th century technology as tricorders. In 1996, Tuvok destroyed the hard drive of Rain Robinson's computer using this method in order to prevent her from further tracking the position of USS Voyager. (VOY: "Future's End")