Hard Disk Drive
A hard disk (commonly known as a HDD (hard disk drive) or hard drive and formerly known as a fixed disk) is a non-volatile storage device which stores digitally encoded data on rapidly rotating platters with magnetic surfaces.
Strictly speaking, “drive” refers to an entire unit containing multiple platters, a read/write head assembly, driver electronics, and motor while “hard disk” (sometimes “platter”) refers to the storage medium itself.
Hard disks were originally developed for use with computers.
In the 21st century, applications for hard disks have expanded beyond computers to include digital video recorders, digital audio players, personal digital assistants, and digital cameras.