Similar to the old video tape VHS vs. Beta tape wars when VCRs first hit the markets, different manufacturers support different computer DVD recordable standards.
Before mere mortals could burn their own DVDs, the DVD-ROM was the first DVD standard. It is a read-only format, where the video or data content is burned onto the DVD once using precision optical machinery at a commercial facility. This DVD type will run on any DVD-ROM-equipped device.
Today, with the excitement of DVD burning on desktop computers, we're all confused and concerned about DVD-R vs. DVD+R formats. And similar to the old video tape VHS vs. Beta tape wars when VCRs first hit the markets, different manufacturers support different standards.
First of all, understand the DVDs created by either a -R/-RW device or by a +R/+RW can be read by most commercial DVD-ROM players. They both work! It is most important that you use the blank media that matches your burner. The very latest burners are dual-format.
Finally, DVD-RW and DVD+RW are the re-recordable DVD format similar to CD-RW.