A
b-side was originally known as the song on the
flipside of a 12" or 7" vinyl single that backed the
A-side, but wasn't the song promoted or received the radio play. Today CD singles have b-sides along with remixes, even though ironically CD singles only have one side that is used. With CD singles dying a slow death today, b-sides are becoming a
rarer commodity. B-sides were originally used to make a single worth the
buyer's money and to get fans to buy the singles along with the album it came from.
B-sides are usually songs that do not appear on the actually album that the A-side appears on, ocassionally it does. The b-side song was usually determined not to fit in with the overall sound of the album or it was considered not good enough to be on the album or just plain leftover tracks, so hence it's usage as a b-side. B-sides have often gotten a reputation of being filler and
sub-par, even though a good majority of the time b-sides are better than a lot of the album tracks, and in some cases, better than the A-side.
Example:
"Autumn Goodbye" is the
b-side to Britney Spears' 1999 single "...
Baby One More Time."
"Heartbreaker" is the b-side to
P!nk's 2006 single "Stupid Girls."