This format refers to a book that is bound with a rigid protective cover. The advantage of hardcover books is that they are much more durable and, aesthetically, perhaps more pleasing to read than softcovers. In addition, most commercial hardcover books have glued or stitched spines and thus, rest flatly on most surfaces when reading them.
Generally, the audiobooks for most popular titles become available along with the release of the original hardcover version.
For more information on the hardcover format, please visit Wikipedia: http://en.wikipedia.org/wiki/Hardcover This Link Will Open A New Window