CD vs. DVD

In the past, if you wanted to store a large amount of data you would use magnetic tape cartridges. Unfortunately, these cartridges were slow, unstable, and expensive. Optical discs hold more data, are more stable and less expensive than magnetic tape cartridges. You may not be familiar with the term optical disc, but you probably own at least a few of them!

The main types of optical discs include:

• CD-ROM (Compact Disc Read-only Memory)—holds up to 650 MB of data on one disc; cannot be written to.
• CD-R (Compact Disc Recordable)—holds up to 650 MB of data; can be written to with special CD recording hardware and software. CD-Rs only allow you to write once to each area of the disk.
• CD-RW drives (Compact Disc Rewritable)—allows you to write and rewrite data to a CD. Holds up to 650 MB of data.
• DVDs (Digital Video Disc or Digital Versatile Disc)—can hold up to 4.7 GB of data on one disc; cannot be written to.
• DVD-Rs (Digital Video Disc Recordable)—holds up to 4.7 GB of data; can be written to with special DVD recording hardware and software. DVD-Rs only allow you to write once to the disk.
• DVD+RWs (Digital Video Disc Rewritable)—allows you to write and rewrite data to a DVD. Holds up to 4.7 GB of data.