Guide Note:

The compact disc is used to store digital data, primarily audio files. Developed in the late 1970s as a joint venture between Phillips and Sony, the CD has rendered records and cassette tapes obsolete as a source for music and other audio recordings. A standard disc can hold up to 80 minutes of content. Eventually, the CD has become further capably enhanced by its ability to include data storage, known as CD-ROMs, and write-once audio data storage, known as CD-R.

Fast Facts:

1. Developer: Phillips & Sony
2. Materials: Polycarbonate Plastic and Aluminum
3. Capacity: 700 Megabytes
4. Sales as of 2007: 200 billion

At the time of their introduction, most consumers listening to audio did so through record players or tape cassette players. The record player used a needle, leading to scratching of LP's. The cassette players were bulky and because it would thread the tape through its complex mechanism, many tapes would stretch or eventually snap from constant use. The CD, playing within a CD Player, would free from scratches and stretches because of the advanced technology of using lasers to read the information contained on the file. Because the CD runs inside the housing unit of a CD Player, it can be replayed thousands of times without the slightest damage to the file itself.