Another major development in publishing has been the merger of sound recording with publishing. Audio books—also known as talking books or books on tape—generally feature actors or authors reading entire works or abridged versions of popular fiction and nonfiction trade books. Indispensable to many sightless readers and older readers whose vision is diminished, audio books are also popular among regular readers who do a lot of commuter driving or who want to listen to a book at home while doing something else—like exercising. The number of audio books borrowed from libraries soared in the 1990s and early 2000s, and small bookstore chains developed to cater to the audio book niche. Audio books are now readily available on the Internet for downloading to iPods and other portable devices. Four hundred—plus new audio books are available annually.