Total HD, also known as Total Hi Def Disc or THD, is a new optical disc format that is a hybrid of both Blu ray and HD DVD.
Warner Home Video announced the hybrid format at CES 2007, although releases will not hit stores until early 2008.
According to Warner, one side will include a dual-layer Blu ray Disc while the other has a dual layer HD DVD.
More recently, Warner announced they hope to have 10 to 20 titles on launch day, which has been delayed.
Since early 2008, Warner has since dropped HD DVD and scrapped all plans for THD. You can read more news on the demise of the format here:
Total HD in the News
Warner's "Total HD" most likely canned for good (21 November 2007)
Warner's Total HD put on 'hold' (15 September 2007)
Warner Home Video HD news
Warner speaks out about Blu-ray deal (11 January 2008)
Warner Bros. goes Blu-ray (4 January 2008)