The Atlantic has a fascinating story out in which reporter Alexis C. Madrigal uncovered through a combination of spam-bot use and access to Netflix VP of Product Todd Yellin, that Netflix has nearly 80,000 of those very specific movie and television sub-genres that it's always showing you.
The bot used returned 76,897 genres to be exact.
As an added bonus, the article also has a fun genre generator that you can play around with:
Another potentially helpful nugget of information mentioned in the piece is that you can access specific genres by using the following URL and plugging different numbers (up into the 90,000s) into the last spot.
http://movies.netflix.com/WiAltGenre?agid=80123, for example, will take you to "Dark Father-Daughter Mysteries". http://movies.netflix.com/WiAltGenre?agid=75738 will point you to "Vampire Made-for-TV Movies".
You could probably spend a good part of your day playing around with that. It should be noted that many of these come up blank.
According to Madrigal, Netflix paid people to watch movies and tag them with "all kinds of metadata," giving them a 36-page training document about how to rate movies on their "suggestive content, goriness, romance levels, and even narrative elements like plot conclusiveness" and things like "moral status of characters".
All of this, as the piece points out, helps Netflix show customers that it really understands the kinds of stuff they like to watch, which can be a big part of keeping them on as subscribers.
According to Yellin (as reported by Madrigal), Netflix also uses the tagging data in its personalization for all movies it shows users.
It all makes you wonder why Netflix will only let you browse through a small set of genres through the navigation in its interface.