Liner notes are the booklets which come inserted into the compact disc jewel case or any sound recording container. They usually include information about the musician, lyrics and other credits to 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 give a form of primitive and incoherently structured (from one studio or label to another) metadata set, which can sometimes help establish some form of order in a private or public collection of sound recordings. There is a special version of the ISBD which addresses the issues involved in trusting the information placed in the liner notes, when the time comes to describe a sound recording in the catalogue of a library.