Hard Disk:
A hard disk (also called hard drive, or hard disk drive) is a non-volatile data storage device consisting of one or more metal platters coated with a metal oxide material that allows data to be magnetically recorded on the surface of platters. The disks rotate at a very high speed. Atypical speed is revvolution per minute (rpm) and ,the newest top models spin at rpm. A hard disk can store more data than floopy disk. It is installed inside the CPU (Central Processing Unit) cabinet.