In terms of recorded music, a bonus track is a piece of music which has been included on specific releases or reissues of an album. This is most often done as a promotional device, either as an incentive to customers to purchase albums they might otherwise not, or to repurchase albums they already own. In contrast to hidden tracks, bonus tracks are included on track listings. Methods and media for sound recording are varied and have undergone significant changes between the first time sound was actually recorded for later playback until now. ... For other uses, see Music (disambiguation). ... An album or record album is a collection of related audio or music tracks distributed to the public. ... In the field of recorded music, a hidden track is a piece of music which has been placed on a Compact Disc, audio cassette, vinyl record or other recorded medium in such a way as to avoid detection by the casual listener. ...

Many international releases — most commonly Japanese releases of European or American albums, but not confined to just Japan, or just music going from West to East — contain a few bonus tracks. These are often B-sides from singles; as the music industry in America and Europe moves much faster than elsewhere, more singles are released and so B-sides are released as bonus tracks so that foreign markets do not miss out. Alternate takes are other tracks often released as bonus tracks. It has also been said that this is the industry's way to get consumers to purchase albums from Japanese distributors, instead of sometimes less expensive imports from the West. World map showing the location of Europe. ... In recorded music, the terms A-side and B-side refer to the two sides of 7 inch vinyl records on which singles have been released since the 1950s. ... A take is a single continuous recorded performance. ...

In the case of promotional CDs free with newspapers (The Sun, Daily Express etc.) they are amateur songs recorded by producers of the CD, to fill up empty space on the disc and to make the amount of songs on the disc up to 15 tracks.