Eno defined ambient music as sound that could be either actively listened to or completely ignored. Loops of different lengths overlap, combine, and separate, never quite repeating. He designed the piece for the diffuse acoustic atmosphere of airports.

Shapes drift into being from frequency data, softly, without urgency. The radial mode circles the centre; the horizontal mode drifts left to right. Nothing resolves. Nothing needs to.

Present but unobtrusive, heard without demanding to be listened to. The first fully realized ambient record, a category Eno named and defined with a single release.

Eno described wanting to make music that would be as ignorable as it was interesting. Not background music in the dismissive sense, but music that did not demand foreground attention.

The methodology: record a short phrase, set it to loop at a length not divisible by the others. Phrases combine, separate, re-combine. The work unfolds differently each time it plays.

Music for Airports arrived during a period when Eno was systematically dismantling his own assumptions about what music should do. The result opened an entire genre, ambient, that continues to expand.