1. COMPACT DISCS & DIGITAL VERSATILE DISCS
CD-ROMS & DVD-ROM
The data cannot be altered.
CD-R & DVD-R
Can have data burnt onto them but not erased.
CD-RW& DVD-RW
Can have data burnt onto them and also erased so that the discs can be re-used.

2. DVD-RAM The discs are much higher quality than normal DVD-RWs .
Can reliably store data for up to 30 years.
They are often used for video and data back-up and archiving.
DVD-RAM discs are used in many camcorders (video recording cameras).

4. BLU-RAY DISC
Its written using blue laser which allows data to be stored more closely.
Has more memory than DVDs.
Used to store very high quality, high definition videos.

5. USES
Distribute all sorts of data: software ( e.g. office applications), music, electronics books (e.g. encyclopedias with sound and video)
DVD- ROMs are also used to save high quality video as they have more memory space.

6. ADVANTAGES
Random access devices.
In CD and DVD- ROMs data cannot be written nor erased from.
Portable.
DISADVANTAGES
Can be damaged and easily.
Due to small size can easily be stolen.