An audio book is a recording of the contents of a book read aloud. It is usually distributed on compact discs (CDs), cassette tapes, or digital formats (such as mp3). The term "audio book" has been synonymous with "books on tape" for roughly 20 years. Cassette tape sales still comprise roughly 40% of the audio book market, with CDs the other dominant format type.

Unabridged audio books are word for word readings of a book, while abridged audio books have text edited out by the abridger. Audio books also come as fully dramatized versions of the printed book, sometimes calling upon a complete cast, music and sound effects.

There are quite a few radio programmes serialising books, sometimes read by the author or sometimes by an actor, most of them on the BBC.

Some books are recorded by a Computer and others by human narrators

The popularity of portable music players such as the iPod have made audiobooks more accessible to people for portable listening.

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