8. Digital Versatile Disk (DVD)

DVDs are amongst the most common methods of copying and backing up data at home.


A DVD is similar to a CD in that it is an optical device and that a laser is used to store the data and read the data.

A single layer DVD can store about 4.7Gb of data.

A double layer DVD can hold over 9Gb of data.

One problem with the DVD is that the different companies which make them have not agreed on a standard format.

Because of this, you will see various kinds of DVD disks for sale: DVD-R, DVD+R, DVD-RW and DVD+RW. You have to make sure that you buy the right kind of disk to go with your DVD equipment.


Advantages of DVDs Disadvantages of DVDs
Very large storage capacity 4.7-9 Gb DVDs do not work in CD drives
Sound and picture quality is excellent, making them ideal for storing films with video and sound. There is no single standard of DVD
DVDs are now mass produced so they are relatively cheap They can be easily damaged by breaking or scratching
DVD drives can read CDs  


Properties of a DVD
Property Notes
Type of storage Optical
Data access Direct access
Cost of storage DVDs cost more per byte of storage than hard disks, magnetic tapes or flash memory. They are less expensive than CDs per byte of storage.
Capacity 4.7 (single layer) to 9 Gigabytes (double layer)
Speed Slower than a hard disk or flash memory, faster than magnetic tape

Fairly portable. Too large to fit into a pocket, but will easily fit inside a bag. Can be carried between home/school/office.


Easily scratched by general wear and tear or by not protecting it in a plastic case. Scratches on the disk surface can damage the data being stored

Needs to be protected from extremes of heat.

Has a limited number of read/write cycles.


If scratched, the data might not be able to be read.

Needs a computer with a DVD drive in order to read the disk. Cannot be read by a CD drive.

Challenge see if you can find out one extra fact on this topic that we haven't already told you

Click on this link: DVD