DVD-A (DVD Audio)DVD-Audio is a high quality multi channel sound format based around the DVD format and designed in time to replace CD.
DVD-Audio discs can have high quality multi channel sound with sampling frequencies up to 192kHz (Standard CD is just 44.1kHz)
Most DVD audio discs can be played back in existing DVD players but cannot take advantage of the high quality uncompressed 24bit 192kHz sound quality unless they are "DVD-Audio" compliant.
Playback on existing DVD players is in compressed "Dolby Digital"
DVD-Audio is a rival format to SACD although many players can now play both formats eliminating the worry over which format will replace CD