Liner notes (also sleeve notes or album notes) are the writings found in booklets which come inserted into the compact disc jewel case or the equivalent packaging for vinyl records and cassettes. They are descended from the notes of text that were printed on the rear side of the cardboard record jacket used to protect a traditional 12-inch vinyl record, i.e., long playing or gramophone record album. The term descends from the name "record liner" or "album liner". On vinyl recordings, the most common placement of these notes would be the paper sleeve inside of an album jacket that served to protect the record from dust (dust sleeve or dust liner, etc.). As the rear covering of an album jacket was applied in early days in a fashion that resembled the tailored lining of garments (overlapping and protecting the edges of the front cover), it's also likely that "liner" could have been a printer's terminology for this back cover area as well.
Such notes often contained a mix of factual and anecdotal material, and occasionally a discography for the artist or the issuing record label. They were also an occasion for thoughtful signed essays on the artist by another party, often a sympathetic music journalist, a custom that has largely died out. However, the liner note essay has survived in retrospective compilations, particularly in box sets.
Liner notes now usually include information about the musician, lyrics, a personnel list, and other credits to people the musicians want to thank and people or companies involved in the production of the music. They also can give details on the extent of each musical piece, and sometimes place them in historical or social context. Liner notes for classical music recordings often provide information in several languages; if the piece includes vocal parts, they will often include a libretto, possibly also translated into several languages.
Liner notes sometimes provide metadata that can help when cataloguing private or public collections of sound recordings. However, the information provided on liner notes varies considerably depending on the studio or label which produced the record.
Increasingly and due to the rise of digital downloads, a digital booklet is being introduced to compensate for the lack of a physical booklet.