DVD / HD DVD hybrid discs
There are two types of hybrid formats which contain standard DVD-Video format video for playback in regular DVD players, and HD DVD video for playback in high definition on HD DVD players. The Combo disc is a dual sided disc with one side DVD and the other HD DVD, each of which can have up to two layers. The Twin disc is a single sided disc that can have up to three layers, with up to two layers dedicated to either DVD or HD DVD. These hybrid discs make retail marketing and shelf space management easier. Another advantage is hardware cross-compatibility. The average consumer doesn’t have to worry about whether or not they can play a hybrid DVD: any standard home DVD player can access the DVD-encoded content and any HD DVD player can access both the DVD- and HD DVD-encoded content.