Compact Disk Drive
Another device used as secondary, permanent storage is the Compact Disk (CD) drive. This device uses a laser beam to burn digital data in the form of Binary code onto the surface of a metallic disk covered in dye and a protective coating. This is called a Compact Disk.
Digital Versatile Disk Drive
The problem with the CD drive is that it has a limited capacity for storage. After all, these days any decent movie needs over 2 GB of storage space. Therefore, the CD drive has been replaced by the Digital Versatile Disk (DVD) drive.
Blu-Ray Drive
The latest optical technology available uses a blue laser of wavelength 405nm and is called Blu-Ray Technology. Since the wavelength of the blue light is shorter than that used by the DVD disk (red light), far more data can be written to the Blu-Ray Disk. A Blu-Ray Disk can store up to 25GB in a single layer.