Adventist Youth Honors Answer Book/Computers/Hard drive
A hard drive is a nonvolatile data storage device. It works by the same principals as a floppy disc, except that it is much faster, has much greater storage capacity, and is usually not removable from the computer. Most hard drives consist of several aluminum platters stacked on a spindle. The platters (or disks) are coated with a material whose magnetic properties are easily detected (for reading) and changed (for writing). The computer's operating system is usually stored on the hard drive as are most of the other programs the computer runs. Data stored on a hard drive will not be destroyed if the computer is turned off.