Audiobooks are usually distributed on CDs, cassette tapes, or digital formats (e.g., MP3 and Windows Media Audio). The term "books on tape" is frequently used as a synonym for audiobooks, but cassette tapes are no longer the dominant media for audiobooks. In 2005, Cassette-tape sales made up roughly 16% of the audiobook market, with CDs sales accounting for 74% of the market, and downloadable audio books accounting for approximately 9%. In the United States, the most recent sales survey (performed by the Audio Publishers' Association in the summer of 2006 for the year 2005) estimated the industry to be worth 871 million US dollars. Current industry estimates hover at around two billion US dollars per year. Most new popular titles put out by the major publishers are available in audio book format simultaneously with publication of the hardcover edition. There are approximately 25,000 current titles on cassette, CD, or downloadable format. Unabridged audiobooks are word for word readings of a book, while abridged audio books have text edited out by the abridger. Audiobooks also come as fully dramatized versions of the printed book, sometimes calling upon a complete cast, music, and sound effects. Each spring, the Audie Awards are given to the top nominees for performance and production in several genre categories. There are quite a few radio programs serializing books, sometimes read by the author or sometimes by an actor, most of them on the BBC.

Kathy Reichs is a forensic anthropologist for the Office of the Chief Medical Examiner, State of North Carolina, and for the Laboratoire des Sciences Judiciaires et de Médecine Légale for the province of Quebec. She is one of only fifty forensic anthropologists certified by the American Board of Forensic Anthropology and is on the Board of Directors of the American Academy of Forensic Sciences. A professor of anthropology at The University of North Carolina at Charlotte, Dr. Reichs is a native of Chicago, where she received her Ph.D. at Northwestern. She now divides her time between Charlotte and Montreal and is a frequent expert witness in criminal trials. Her work as a forensic anthropologist is internationally recognized. She has traveled to Rwanda to testify at the UN Tribunal on Genocide, helped identify individuals from mass graves in Guatemala, and done forensic work at Ground Zero in New York. For her work with CILHI she has identified war dead from World War II; from all of Southeast Asia – she even examined the remains from the tomb of the Unknown Soldier.