In general terms, this phrase refers to any recorded edition of a published document (magazine, textbook, and novel). More specifically, in the world of visual impairments, it refers to the commercially prepared editions of documents offered to the blind community through various organizations, libraries, charities and educational institutions.
Production approaches vary from country to country. Most countries use a standard cassette tape on which to record the information. Adjustments are made to the speed and stereo track use to allow for more information to be recorded on one tape, requiring the use of a special tape player for listening.
Some effort is being made toward digitizing the books from some libraries and distributing them on Compact Disks; however, this approach is in its infancy.