iDVD can burn your projects to discs with the following formats:
DVD-R: 4.2 gigabytes. Can be used only once. Recorded data becomes permanent on the disc. This is the recommended format for projects that can fit on a single-layer disc.
DVD-RW (Rewritable): 4.2 gigabytes. Can be used more than once. Recorded data can be erased, and the disc can be rerecorded numerous times.
DVD+R: 4.2 gigabytes. Can be used only once. Recorded data becomes permanent on the disc.
DVD+RW: (Rewritable): 4.2 gigabytes. Can be used more than once. Recorded data can be erased, and the disc can be rerecorded numerous times.
DVD+R DL (Double Layer): 7.2 gigabytes. Provides two recordable layers on a single-sided disc. This is a good choice for large projects.
If you are using your SuperDrive to burn the DVD, make sure it supports the media you choose. The SuperDrive in your Mac can write to DVD-R and DVD-RW discs, and most newer SuperDrive optical drives can write to DVD-RW, DVD+R, DVD+RW, and DVD+R DL discs as well.
Choose disc media with read and write speeds supported by the speed of your SuperDrive. For best results, use Apple discs.
If you are using an external, third-party DVD burner, you should consult the product documentation to make sure it supports the media you plan to use.
For information on purchasing blank DVD discs, go to the Apple Store website.