The Atlantic's Alexis C. Madrigal has a fascinating piece on how Netflix built a database of more than 79,000 micro-genres that it uses to classify its movies and TV shows:

What emerged from the work is this conclusion: Netflix has meticulously analyzed and tagged every movie and TV show imaginable. They possess a stockpile of data about Hollywood entertainment that is absolutely unprecedented. The genres that I scraped and that we caricature above are just the surface manifestation of this deeper database.

Netflix cooperated with my quest to understand what they internally call "altgenres," and made VP of product innovation Todd Yellin, the man who conceived of the system, available for an in-depth interview. Georgia Tech professor and Atlantic contributing editor, Ian Bogost, worked closely with me recreating the Netflix grammar, and he programmed the magical genre generator above.