CDs and DVDs

CDs and DVDs
Mac Tip #101/14-May-2003

Some of my clients have been a bit confused about CDs and DVDs — what they are, what they do and how much information they can hold.

Both CDs and DVDs are thin, round, flat shiny discs, a few inches in diameter.

You can buy or borrow commercial CDs and DVDs. These are likely to contain music (CDs and DVDs) or movies (DVDs).

Most people have played a music CD at some time, probably in a home stereo. You can also play music CDs in your Mac. In recent years iTunes handles that process.

Other CDs are used to hold computer software or other information for a computer. Some have software intended for Macs, while others have software not intended for Macs but instead for Windows or other operating systems.

Commercial DVDs generally hold a full-length movie or several episodes of a TV show. You can play them in a stand-alone DVD player or in certain Macs equipped with a DVD drive.

Many modern Macs can not only play CDs and / or DVDs but also create them.

A CD holds about 650 Megabytes of data. That could be music, software, video clips, wordprocessing files, databases, emails or anything, and it’s likely to be a whole lot of them. Many of my clients who tell me they have “a lot of stuff” turn out to have maybe 20 Megabytes of data. They could fit that and another 30 lots of the same onto one CD! One CD holds about the same amount of information as 465 floppies.

If you have a Mac capable of creating CDs you can buy a blank CD very cheaply and easily “burn” your data onto it. See Make a CD.

If you have a Mac with a Superdrive, capable of creating DVDs, then you can burn DVDs. Since a DVD can hold about 4.5 Gigabytes it’s ideal for movies and large stores of photos or music. All those items require a lot of storage space. One DVD holds about as much as 7 CDs (or 3255 floppies). That’s a lot of data. If your Mac can burn DVDs then you’ll also have the iDVD software which allows you to create DVDs just like the ones you can hire from the video store.

Now that’s a fun thing to do!