Hidden track

In the field of recorded music, a hidden track (sometimes called a secret track or ghost track) is a piece of music that has been placed on a CD, audio cassette, LP record or other recorded medium in such a way as to avoid detection by the casual listener. In some cases, the piece of music may simply have been left off the track listing, while in other cases more elaborate methods are used. In rare cases a "hidden track" is actually the result of an error that occurred during the mastering stage of the record's production.

A vinyl record may be double-grooved, with the second groove containing the hidden tracks. Examples of double-grooving are Monty Python's "three-sided" Matching Tie and Handkerchief, Tool's Opiate EP and Mr. Bungle's Disco Volante.

On indexed media such as compact discs, double-grooving cannot be used, but there are additional methods of hiding tracks, such as:

Often it is unclear whether a piece of music should be considered a hidden track. For example, "Her Majesty", which is preceded by fourteen seconds of silence, was originally unlisted on The Beatles' Abbey Road but is listed on current versions of the album. This is one of the first instances of a hidden track. The song snippet at the end of Sgt. Pepper's Lonely Hearts Club Band is considered by some to be a hidden track, by others to be noise not worthy of such a designation, and by others to be part of "A Day in the Life".

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