Page 3 of 8: Writable Formats
Imagine if there were 5 different kinds of VHS tapes and they all looked identical but were not  that is basically where the DVD standards world is right now. There are essentially 5 versions of writable DVD that you need to understand. They are: DVD-R, DVD-RAM, DVD-RW, DVD+RW and DVD+R. The distinctions are actually based on how the data is written to and read from the disk, and this differentiation is difficult to translate to the physical world, however one example might be language.Imagine if the entire world agreed on a single language for all written documents, say English. In the United States we would continue to create English documents and books in which one reads left to right. But another country might prefer to write and read English right to left. And yet another, top to bottom, and so on until the effect became that although all documents were created in a single language, it would be very difficult for a person from one country to read a document from another country. DVD recording is in a similar state of confusion. DVD is such a nascent technology that these issues have yet to work themselves out, so you have no choice other than understanding them all. One easy way to think about the formats is as 5 completely different kinds of DVD disks.