DVD-ROM - 'Read only, manufactured by a press', such as a computer game or dvd with a movie from a shop.

DVD-R - 'Recordable once' , can record data only once.

DVD-RW - 'ReWritable', can be recorded over numerous times. Because this has a '-' it means its supported by Philips, Sony, Dell, Ricoh and Yamaha.

DVD-RAM - 'Random access rewritable'

DVD+R/RW - 'Recordable once' , can record data only once.

DVD+RW - 'ReWritable', can be recorded over numerous times. Because it has a '+' it means its supported by Panasonic, Apple Computer, NEC, Pioneer and Samsung. Visit the website for the DVD+RW Alliance for more information. The group states on their website that they aim ' to develop and promote a universally compatible, rewritable DVD format to enable true convergence'.

DVD-R DL - 'Double layer', provides two recordable layers on a single sided DVD disc.

DVD+R DL - 'Double layer', provides two recordable layers on a single sided DVD disc. Again the difference between '-' and '+' is the companies who support the format. Which means they sometimes only allow the '-' or '+' format to play on their machines.