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The Differences Between CDs and DVDs
So What Is So Different About CDs and DVDs
CDs and DVDs are two completely separate and distinct pieces of technology but to the naked eye they look exactly the same. There are many different things between the two, such as what they hold and how much they can hold.
It becomes apparent how the big difference in storage capacity is achieved when you understand how data is written to a CD or DVD. A laser is used to burn pits around a spiral groove in 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. More pits in the same amount of surface area results in a larger amount of information and explains why a DVD is capable of holding so much more data than a CD.
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. The pits and lands (where there are no pits) on the DVDs and CDs represent ones and zeros. When the disc is read the laser moves around the discs surface and is reflected off the lands but not off the pits. Optical technology reads the data and converts into the ones and zeros that your computer can then understand.
Because the spiral groove is narrower on a DVD than a CD it is subsequently longer and able to hold more data. The most common DVD format can hold 4.5GB of data which is approximately six times more than a CD which only holds 700MB. Other DVD formats can hold a lot more because they are double sided or dual layered.
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 technology also has a much faster rate of reading and processing data. A 52X CD-ROM can read data at 8.4Mb a second while a 24X speed DVD can read data at about 32MB a second. This is a massive speed increase.
DVDs are still the most popular choice for movies and data storage these days but 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 CDs and DVDs in regards to packaging and promotion have a look at the following website Packaging CDs and DVDs.