The DVD-Forum, which includes companies like Philips, Sony, Hitachi, Mitsubishi, Pioneer and Toshiba, prefers the DVD-R and DVD-RW formats. The DVD+RW Alliance, consisting mostly of hardware and media manufacturers such as HP, Yamaha, Ricoh and Verbatim, backs DVD+R and DVD+RW formats.

Computer-based DVD burners can use any of the formats, but stand-alone DVD players/recorders are either one or the other. Currently, DVD-R has 42 percent of the market share for one-time writable media and DVD+R has 41. For re-recordable discs, DVD+RW leads DVD-RW by a margin of 58 percent to 33 percent.

The industry is also divided on the future format for recording high-definition video. The DVD-forum and several Hollywood studios prefer the HD-DVD format, while other industry players argue for the Blu-Ray Disc format, which offers 50 gigabytes of capacity compared to HD-DVD’s 30.

Why was this coding system invented? Movies are not released at the same time worldwide. A movie may open in the United States months before it opens somewhere else. DVDs may already be out in America before the theatrical release in another country.

Without DVD coding, a person’s American friends could send them a DVD of a movie still playing in theaters in the recipient’s country, which would cut into box-office profits.

DVD coding also allows companies to set different prices in different regions, based on their purchasing power. If U.S. consumers could order DVDs from a poorer country where they sold for a couple of dollars, sales in the U.S., where DVDs can cost US$15 and up, would suffer.