What Are They?
Hard Disc Drives (HDD)
A hard disk drive (HD, or HDD) is a device that stores and retrieves information. A hard drive can be used to store just about any type of data, including pictures, music, videos, and text documents. Computers have a hard drive and use it to store files for the and software that run on the computer, as well as files created or downloaded to the computer by a user.
Optical Drive (OD)
Any information or data that is sent to a computer for processing is considered input. Input or user input is most often sent to the computer using an input device such as a keyboard or mouse. The picture is an example of input being sent from the computer keyboard to the computer.
Operating Systems / Other Software
An operating system