If you’ve been paying any kind of attention to music in the past twenty years, you know what the business of making, spreading, and listening to music has changed in almost every way. New technology, new distribution platforms and a growing digital world have shaken up the system entirely and only show signs of further change. Off Book: The Evolution of Music Online, a short film from PBS, will talk you through “these massive changes, and reveal how music blogs and websites have arisen as the new arbiters of quality.” With commentary from such fine internet music trendsetters and game changers as the founder of Hype Machine, a senior editor at Pitchfork, the co-founder of FADER, and the VP of Creative Development at Vimeo, it’s a good overview of the changing face of music. Click through to watch, and let us know what you think in the comments.