The world of online music has been evolving and expanding for a long time now. As more people listen and discover more music online, all of our listening, viewing, 'liking', and tweeting creates a mass of data ripe for aggregation and analysis. The volume is staggering.

A great way to hear new music is to stream on Spinner, NPR, and 3voor12 the week prior to their release but those plays are not counted here. I can understand why they don't track those plays as they are just a sampling of the music that you may not suit your musical palate. And there are other streaming sites that are of questionable legality when it comes to copyright that makes sense not track.
It's an incomplete picture of trends in online music but gives you a sense of the scale of our online engagement with music. BP
It's an incomplete picture of trends in online music but gives you a sense of the scale of our online engagement with music. BP