A storage device is any computing hardware that is used for storing, porting and extracting data files and objects. It can hold and store information both temporarily and permanently, and can be internal or external to a computer, server or any similar computing device.
hard disk drive is an electromechanical data storage device that uses magnetic storage to store and retrieve digital information using one or more rigid rapidly rotating disks coated with magnetic material.
Tertiary storage or tertiary memory provides a third level of storage. Typically, it involves a robotic mechanism which will insert and dismount removable mass storage media into a storage device according to the system's demands; such data are often copied to secondary storage before use.