[Arubis]

The Pandora algorithm -- and Pandora's positioning -- is truly a product of its time. You'll want to look into the Music Genome Project (whose very name dates it; the Human Genome Project finished in 2003), but equally influential was the big labels' stranglehold on legal music distribution. When Pandora started and for years of profitability, they had no deals with major record labels, instead promoting small indie artists on the basis of their recommendation engine. If they were going to survive, that engine had to be _excellent_.