So what is a b-side? it is the secondary recording on a two-sided single, opposite the promoted A-side, historically the track expected to get less airplay and attention. What follows is where it comes from, what it actually means, three records to hear it for yourself, and the traps to avoid. Get it straight once, and a whole shelf of prog records suddenly reads more clearly.

Where it comes from

The A-side and B-side distinction comes from the two physical sides of the 45 rpm single, and the convention firmed up in the early 1960s, when labels began deliberately choosing which track to push. The other side was left for whatever the band or label thought suited it.

For prog fans the B-side became a happy hunting ground, since bands often used it for non-album tracks and experiments that turned up nowhere else.

What it actually means

A B-side is defined by its place on the single, opposite the plug side, rather than by any quality of the music. It might be an exclusive song written off for the flip, an album track re-used, or an oddity that did not fit the parent LP. Because they were treated as secondary, B-sides are often where the surprises hide.

In prog these flip sides have become collectors’ quarry, gathering non-album songs, edits and experiments that later turn up as bonus tracks on expanded reissues. A great B-side can be as strong as anything on the album it accompanied, and part of the pleasure of the deluxe-edition era is hearing these once-obscure tracks restored to the catalogue.

Hear it for yourself

Three records make the idea concrete — one to start with, and two more that prove it was no accident.

Pink Floyd — Careful with That Axe, Eugene (1968): a celebrated non-album B-side.

Genesis — Nursery Cryme (1971): album material also pressed on a single’s flip.

Rush — Moving Pictures (1981): a catalogue since expanded with rarities and flips.

None of the three is the only example you could pick, but together they make the idea easy to recognise the next time you meet it in the wild. Once your ear knows what to listen for, you will start hearing it everywhere, and the term stops being jargon and starts being useful.

Common confusions

It is most often confused with an ordinary album track. A B-side is defined by sitting on the flip of a physical single; it may be an exclusive recording or an album cut re-used, but the format is what makes it a B-side.

As always, the label is a guide rather than a cage. Real records slip between categories all the time, and a term like this one is most useful as a way of hearing more clearly, not as a boundary to police. When the tag and the music disagree, trust the music, and treat the word as a shortcut for a sound you can already recognise.

Go deeper

Back to the progressive rock glossary to keep browsing, or read on about an ep, a double album, a bootleg recording. For the records these ideas live in, see the concept albums, and if you are just starting out, the beginner’s guide is a gentler way in than any single definition.

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