Before we start our list of the Best B-Sides Ever, we should probably explain the terminology a bit. After all, post-iPod generations may be unfamiliar with the old 45-rpm single – a vinyl anachronism that contained one song on each side.

Perfect for radio and jukebox airplay, the single was generally meant to showcase the prospective hit on its A-side with an additional song on the B-side. Unfortunately, these B-sides would typically include throwaway tracks from the concurrent album or, worse still, even instrumental versions of the a-side. Then there were moments like these, when lucky listeners would flip the single over – only to find a non-album gem, something never before heard and never found again.

Some became hits, some just obscure favorites. Eventually, some of them even found their way into compilations in the compact-disc age. But they started out as found objects, unique to the medium. Here's our list of the 10 Best B-Sides Ever:

  • 10

    'Total Eclipse' (1982)

    Iron Maiden

    Chosen to back "Run to the Hills" as an advance single while Iron Maiden worked furiously to complete The Number of the Beast. the propulsive "Total Eclipse" would have made a great album that much greater. Steve Harris copped to it in Iron Maiden: Run to the Hills, the Authorized Biography, saying Iron Maiden simply "chose the wrong track as the B-side. I think if 'Total Eclipse' had been on the album instead of 'Gangland' it would have been far better."

  • 9

    'The Sweetest Thing' (1987)

    U2

    Bono reportedly wrote "The Sweetest Thing" as a Peter Criss-style apology after staying late during sessions for The Joshua Tree on his wife's birthday. And for years, it could only be found on the B-side of U2's "Where the Streets Have No Name" single. A little over a decade later, U2 returned to the track, re-recorded it and issued "The Sweetest Thing" as a single. No word on what Bono did to prompt the second apology.

  • 8

    '51st Anniversary' (1967)

    Jimi Hendrix

    A rambling rocker, "51st Anniversary" finds Jimi Hendrix following a happily-ever-after marriage backward toward its point of dissolution even as Noel Redding and Mitch Mitchell make a furious racket. Sean Egan, in Jimi Hendrix and the Making of 'Are You Experienced,' notes that this Jan. 11, 1967 session was a first for Hendrix: He tried overdubbing, eventually stitching five different guitar performances together to create this way-cool "Purple Haze" B-side.

  • 7

    'Carry Me Home' (1977)

    AC/DC

    The bouncy, boozy "Carry Me Home" was, forever, one of the great AC/DC rarities – a B-side to "Dog Eat Dog" released only in Australia. Those who found it were treated to one of Bon Scott's great story-songs – and some of mid-'70s bassist Mark Evans' final recordings with the group. "Carry Me Home" finally received wide release on 2009's Backtracks.

  • 6

    'Yellow Ledbetter' (1992)

    Pearl Jam

    Appearing opposite "Jeremy," this B-side gem would actually fit nicely next to Hendrix's "51st Anniversary" – being as it starts with this melancholy Mike McCready lick straight out of Hendrix's handbook. A soaring vocal and extended guitar meltdown follow, making "Yellow Ledbetter" one of Pearl Jam's better distillations of the old-school classic-rock aesthetic. DJs thought so too, and this B-side ended up becoming a radio hit on its own.

  • 5

    'Murder By Numbers' (1983)

    The Police

    This wickedly smart Police obscurity found a home opposite the blockbuster "Every Breath You Take" single – and possessed a similar twist, if you listened closely. The A-side turned on love's transition into obsession, while the B-side finds Sting stealthily equating political sociopaths with the every-day kind.

  • 4

    'Shut Out the Light' (1984)

    Bruce Springsteen

    As with the Police's single before it, this Bruce Springsteen B-side serves to amplify the craftsmanship – and even the message – of its more familiar A-side. After all, there were some who misinterpreted Bruce Springsteen's harrowing "Born in the U.S.A." as being some sort of celebratory anthem. He left no room for misinterpretation, however, when it came to "Shut Out the Light" – a bare-knuckled tale of Vietnam's aftermath inspired by Ron Kovic's darkly enlightening book Born on the Fourth of July.

  • 3

    'Hey Hey What Can I Do' (1970)

    Led Zeppelin

    Just why "Hey Hey What Can I Do"' which originally found a home on the flip side of "Immigrant Song," stands as the only non-album B-side ever released by Led Zeppelin remains something of a mystery. Perhaps it was because the song took the folk influences that dominated Led Zeppelin III to their zenith, with Robert Plant principally working in his mystical lower register over a jangly acoustic. Was it, you know, too jangly? No matter, "Hey Hey" became a classic rock-radio staple anyway.

  • 2

    'Silver Springs' (1977)

    Fleetwood Mac

    Stevie Nicks submitted "Silver Springs" – a song focusing on her faltering relationship with Lindsey Buckingham – for the Rumours album, only to see it relegated to the B-side of the "Go Your Own Way" single. She never forgot "Silver Springs," however, returning to it some two decades later for a Fleetwood Mac reunion concert recording – after which, it promptly won a Grammy.

  • 1

    'I Am The Walrus' (1967)

    The Beatles

    History has shown that the Beatles' – really, Paul McCartney and George Martin's – decision to make "Hello Goodbye" the A-side to "I Am the Walrus" earned them another No. 1 song. But that throwaway pop ditty will never have the psychedelic gravitas of John Lennon's titanic B-side. Worse still, the argument over this single sowed seeds of discontent that would ultimately split the Beatles. Speaking about it later, Lennon said he came to a revelation: "I got sick and tired of being Paul's backup band."

More From Ultimate Classic Rock