HDD

A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magnetic material.

HDD were typically large secondary storage devices with multiple spinning platters of magnetic coated material and moving heads used to write data for subsequent retrieval. Over time HDD have become smaller to the point of miniaturisation.

There is now a wave of solid state drives (SSD) that are replacing HDD in the commodity equipment market, especially in laptops.