This tweet from Netflix and some [similar stuff from Spotify](https://qz.com/848463/spotify-launches-a-set-of-billboard-ads-that-mock-the-musical-tastes-of-its-users/) is some really cute marketing but I've seen a few people worried, calling it a privacy violation and claiming that anyone at these companies can just access all your personal data. So I'm going to try and put those worries/fears to rest. Netflix, et al do collect [heaps of analytics](https://blog.kissmetrics.com/how-netflix-uses-analytics/) about each movie/song that's listened too, how long for and whether it was skipped or rated up/down. That's part and parcel of how they decide to option new series, rotate their catalogues, etc. Now on some level this information will be tied to a user account: otherwise how else would things like their [recommendation engines](https://medium.com/netflix-techblog/learning-a-personalized-homepage-aa8ec670359a) work? However access to information for individual users is strictly controlled and also heavily logged. Random employees can't look up your account and see your secret obsession with Groundhog Day. Doing queries directly against users usually requires sign off from higher levels in both customer service, regulatory, and security services and thanks to privacy laws usually have to have a reason for it (legal investigations, direct requests from customer for information held about them, etc). And from a technical perspective, trying to find out the number of people who watched something by looking against every user account is really inefficient and impractical. Instead big data companies do "aggregate analytics", which means that rather they store data about viewer counts, relationship between different shows (based on intersections of viewers, etc) without involving user data or PII. This data is more readily available for staff to query against because it *doesn't* link to viewers. Which is how they can run cool queries and make cute posts without snooping on you. Also typically the aggregate analytics aren't stored even in the same database platform as personal user data. Usually the former goes through an extraction-transform-load process into a specially designed platform for doing data analysis. **TL;DR:** Netflix/Spotify aren't looking up your account to judge your media habits.To the 53 people who've watched A Christmas Prince every day for the past 18 days: Who hurt you?
— Netflix US (@netflix) December 11, 2017