John Naughton, The Guardian:

The advent of the compact disc in the early 1980s meant that recorded music went from being analogue to digital. But CD music files were vast – a single CD came in at about 700MB.

And:

In 1993, researchers at the Fraunhofer Institute in Germany came up with a way of shrinking audio files by a factor of 10 or more, so that a three-minute music track could be reduced to 3MB without much perceptible loss in quality. They called their new standard MP3.

And:

In 1999, a teenage geek named Shawn Fanning created a neat software system that enabled internet users who had MP3 tracks on their PCs not only to find others with similar assets but also to exchange these tracks with one another. Fanning called his file-sharing system Napster, released it on the internet and in the process changed the world.

Nice little look back at the market forces that made the music industry ripe for disruption. Enter Steve Jobs and Apple. And iTunes of course.