University of Oregon

More about CDs and DVDs (Optical Media)


CDs and DVDs are known as optical media because lasers are used to read and write data to the disc. There are two types of CDs and DVDs: recordable and rewritable. Recordable (abbreviated -R) means the disc can be written to only once. Rewritable (abbreviated -RW) means the disc can be written to multiple times. For data backups, -RW is the best choice because your data changes over time.

Disc Capacities & Uses

CD: 650MB to 850MB

Good for:

  • Playable CDs
  • Documents
  • Program installation files

DVD: 4GB to 8GB

Good for:

  • storing lots of pictures
  • some music
  • smaller video files
  • burning whole movies