HD DVD players will play regular DVDs, and special HD DVD discs will contain both formats on one disc. That means consumers will only have to buy one movie regardless of the type of player they have.

so you can't play a Blu-ray disc on a DVD or CD player. However, Blu-ray Disc players can play DVDs and CDs, and some play more disc and USB-based media file formats. In late 2015, the Ultra HD ...