DVD Recording Formats
The reasons behind different DVD formats.
Since the initial development of the DVD disc, different technology brand manufacturers have supported different DVD formats; Pinoeer took to the DVD -R, Philips to the DVD +R. When DVDs were first launched there was a concern amongst consumers that a "Betamax" situation would unfold where one format took the lead and the other became redundent meaning some customers had wasted money on a future unsupported DVD format. This however has been avoided to most extents as most DVD players and recorders have developed to support all formats (plus and minus).
However some of the lower end machines may still only support one format causing potential problems when purchasing DVD discs. Make sure you know which DVDs your player, drive or recorder supports.
In addition to the +/- rivalry, you should be aware of the difference between "R" and "RW". Whereas the "R" format means you can only record on a disc once, "RW" discs are Re-Writable allowing you to delete and edit programs again and again. Not all machines support the RW format so check that too.