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The Differences Between CDs and DVDs Are Microscopic

Even though both CD and DVD disks have the same media size and shape, the things they have in common end there.  There are many different things between the two, such as what they hold and how much they can hold.

The reason for the big difference in the amount of data storage will become apparent when you understand how data is written to or burned to CDs and DVDs.  As the disc spins a laser is moved across the surface to burn pits in a spiral groove around the disc. Lasers have a wave length and the longer the wave length the bigger the pit. DVD lasers have a substantially smaller wave length than a CD laser. A smaller pit obviously takes up less space and ultimately resulting in the ability to store more information in the same amount of surface area.

Digital data is data that is stored as a series of ones and zeros. DVDs and CDs are digital data storage mediums so everything, including audio and video, is stored as ones and zeros. Pits and lands (an area where there are no pits) represent ones and zeros. When the disc drive is reading data the laser is reflected off the lands but not off the pits. The information from the laser is converted by a microprocessor into digital data that a computer can understand.

Because the spiral groove is narrower on a DVD than a CD it is subsequently longer and able to hold more data.  The average single layer DVD holds 4.5 GB of information, while a CD holds a mere 700 MB..

As the pits on a DVD are smaller the physical make up of a DVD has to be different to a CD in order to allow the laser to focus on them.  A thinner plastic substrate must be used, giving the laser less material and less depth to get through to the surface.

DVD drives are also capable of much higher data throughput than a CD drive.  The difference in speed is very large with a 52X CD drive reading data at 8Mb a second and a DVD 24X drive reading data at 32MB second.

DVDs are the most popular choice for movies and data storage these days but they are slowly being taken over by Blu-Ray. CDs are still widely available but I imagine they will eventually go the way of the floppy disk as new technologies keep emerging. For more related information on Compact disks and DVDs in relation to packaging and marketing go and visit this website CD DVD Packaging.

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