For most of its modern life, pop music has been defined by hit singles. Whether heard via the milkbar jukebox of the Fifties or today's digital music channels, the snakes-and-ladders journey which the single enjoys has obsessed both the performers and their audience. Until the Seventies, when pop became rock and albums took over the serious business of money-making, hit singles drove the business. Every time music seems moribund, something happens to rejuvenate the singles market: punk in the Seventies, dance music in the Nineties.

Last year, though, the single had its worst year in Britain for a long time. Overall sales slumped by 8 per cent. Only two singles entered the magic million-seller category. One was Hear'Say's debut "Pure And Simple", a manufactured hit if ever there was one. The time when the hit single was a kind of daily currency, uniting a nation that could whistle the number one, has vanished. Ruthlessly segmented by marketing formats, the pop singles market has become far too complicated for anyone but the most committed of professionals to understand.

Singles have long been seen by the industry as the most important kind of sales tool, the trailer for the album. Punk's culture of independence rocked that idea, but dance music's revolution was more far-reaching: most of the major dance hits came from artists who would rather put out strings of singles than turgid CD-length masterworks, and many were created away from the grasping hands of the major labels. Inevitably, the only dance albums that people wanted were compilations. The hook of the pop hit was displaced by the pulse of the dance success, and the dependence on dance records being "created" rather than "played" began to disperse pop's personality cult. Every week, there are artists in the singles chart you'll neither know anything about nor ever hear of again: there have always been one-hit wonders, which was part of the hit single's charm, but dance culture created a turnover so fast that anonymity in the field became inbred.

The never-ending fad for remixes led to singles becoming bloated with multiple versions of the original track. The old vinyl format of the EP (extended play, in case you've forgotten) used to be a handy pocket-sized edition of an LP. CD singles, corpulent with remix "bonuses", became half-cocked albums, except it was really the same piece of music padded out to exasperating length.

A long single should be a contradiction in terms. Three minutes was always the sanctified length of the classic single, although many of the greatest weren't even that long. When Richard Harris released a marathon version of Jimmy Webb's ludicrous "MacArthur Park" in 1968, it seemed akin to a Bruckner symphony lumbering into the charts. Nobody would bat an eardrum at it now. Attention spans may be shrinking, but singles now seem to go on for longer and longer.

The weary inevitability of modern hits relying on old hits hasn't helped, either. The Beatles used to cover Chuck Berry and the Isley Brothers, but they saved that for their Hamburg days and their early LP tracks. Many of last year's bestselling singles were flavourless remakes of distinctive originals. Atomic Kitten's soundalike revamp of the Bangles' "Eternal Flame" and Geri Halliwell's take on the Weather Girls' "It's Raining Men" were both pointless revivals, but they were forced on us so relentlessly that each ended up among the 20 biggest hits of the year.

Business pundits often say that you can't guarantee hits, but that is only partly true: so powerful are the big labels when it comes to pushing their favoured acts that, provided the formula isn't too off-track, success has a knack of falling into place. The more "independent" strands of the business become the ones that suffer, when the majors figure out how to rationalise something successful that has come out of the margins. So it is with singles: last year's slump hit the smaller labels hardest, suggesting that we are again in a humdrum period of corporate routine. And suddenly, saturated by pop music everywhere, maybe we're bored with the once-exciting life of the single, too. When being top of the pops matters only to the artist's accountants, a chorus of indifference is going to be our chartbound sound.