Pandora and similar sites

My wife discovered Pandora a couple of years ago. So, I've had some familiarity with the site. One of the most impressive aspects of Pandora is how they must index or catalog bands and genres. It seems to me they do a pretty good job of connecting the various related components of bands, songs, and genres. This is admirable because music is probably the most subjective of the arts, and their ability to identify relationships between these various entities seems improbable. I believe they use a computer algorithm to associate these relationships, and this is even more impressive than a human cataloging those same associations. I did set up a new account for this blog, and the reference band that I used is my favorite band under the age of 30 years, the mighty Arcade Fire.