Red Book CD: The original industry standard that gave the specifications that all CD players had to be able to play. This is a disc no more than 74 minutes in length with a dynamic range of 16 bit and a sample rate of 44.1kHz. It must have a table of contents and a PQ (timing) track that is suitable for audio CDs. This must include track marker timings, gaps between tracks, disc time elapsed, track time elapsed, countdown modes for the disc and for tracks etc.
CD-ROM: Compact Disc Read Only Memory. This usually refers to a data CD that can be read by a computer, not by an audio CD player. It cannot be written to by the computer.
DVD5: A single sided, single layer DVD disc. It can contain up to 120 minutes of high quality video, or up to 4.38GB. They are often advertised as being 4.7GB, but this is untrue. The 4.7GB capacity refers to the Japanese Gigabyte which is defined as 1,000 MB, rather than the 1,024GB we use in the West.
DVD9: A single sided, dual layer DVD disc. A DVD9 can hold up to 4 hours of video or 7.95GB of data.
DVD10: A double sided, single layer DVD disc. Think of it as two DVD5s glued together, back to back. Printing is only possible around the hub as both sides contain data (up to 120 minutes or 4.38 GB per side). This disc has to be turned over for the other side of the disc to be read, much like an old cassette tape.