What Is A DVD?

Date First Published: 20th June 2023

Topic: Computer Systems

Subtopic: Computer Hardware

Article Type: Computer Terms & Definitions

Difficulty: Easy

Difficulty Level: 2/10

CONTENTS

Storage Capacity
How Do DVDs Read Data?
DVD Formats
Difference Between A DVD and A CD
History

Learn about what a DVD in this article.

Stands for a Digital Video Disc or Digital Versatile Disc. A DVD is a type of optical media which can store any kind of digital data. It is most commonly used for storing films, music, and video games for distribution by suppliers. Other uses include storing computer files and software programs. A DVD can be read and played by any device with an optical drive.

Storage Capacity

The storage capacity of a DVD varies, depending on the number of sides and layers. Double-layer and double-sided DVDs can store more data than single-sided and single-layer discs. A single-sided and single-layer disc is the standard DVD, which is enough for 2 hours of video at DVD quality.

Single-sided, single-layer disc - 4.7 GB. Supported by the DVD+R/RW and DVD-R/RW formats.
Single-sided, double-layer disc - 8.5-8.7 GB. Supported by the DVD+R and DVD-R formats.
Double-sided, single-layer disc - 9.4 GB. Supported by the DVD+R/RW and DVD-R/RW formats.
Double-sided, double-layer disc - 17.08 GB. Supported by the DVD+R format.

How Do DVDs Read Data?

DVDs read data by using a laser to mark the disks in a pattern. A light is then bounced off the disk and is read back differently depending on whether the light bounces off a marked or unmarked area. Marked areas represent 0’s in binary and are known as 'pits' and non-marked areas represent 1’s in binary and are known as 'lands'.

DVD Formats

Below are the different types of DVD formats. Whilst these have caused a lot of compatibility issues and confusion in the early 2000s, most DVD drives now support all formats except DVD-RAM.

DVD-R - Stands for Digital Video Disc Recordable. DVD-R is a disc format that can only be written to once. Data is permanently written on the disc and cannot be erased or modified.
DVD-RW - Stands for Digital Video Disc Rewritable. DVD-RW is a video disk format where recordings can be made and erased several times.
DVD-RAM - Stands for Digital Video Disc Random Access Memory. DVD-RAM is a rewritable and erasable disc format which supports advanced defect management and error correction, making them more reliable, but slowing down the maximum data transfer rate.
DVD-ROM - A read-only DVD format which is used to permanently store digital data. It is similar to CD-ROM but has a larger storage capacity.

Difference Between A DVD and A CD

DVDs and CDs look very similar in that they are both the same size and have a labelled and unlabelled side where the data is read by a laser, but the main difference between a DVD and a CD is that a DVD is capable of storing much more data than a CD. Compared to a CD, a DVD can hold seven times as much data. Due to the smaller storage capacity of CDs, they are most commonly used to store audio content rather than video content. DVDs represent the second generation of CD technology.

History

DVDs were invented and developed in 1995 by Sony Corporation and Philips Electronics NV when they agreed on a common format for their competing second-generation CD technologies. They were first available on 1st November 1996 in Japan. The first known films on DVD were "Twister" and "Mars Attacks" released by Hollywood. On 31st March 1997, DVD players were first released for sale.