Novelty suffers, too. By one estimate nearly three-quarters of streamed songs are over 18 months old. Compared with the raucous explosion of genres that characterised popular music until the 2000s— hip hop in all its iterations, the innovation of golden-era British dance music—contemporary music can seem oddly flat.

Spotify's Playlist in a Bottle is a time capsule that users made a year ago, sharing the music that resonated the most at that time. Here's how to see it.