“Only in the middle of the past decade, though, did recommender systems become a pervasive part of life online. Facebook, Twitter, and Instagram all shifted away from chronological feeds—showing messages in the order in which they were posted—toward more algorithmically sequenced ones, displaying what the platforms determined would be most engaging to the user. Spotify and Netflix introduced personalized interfaces that sought to cater to each user’s tastes. (Top Picks for Kyle!) Such changes made platforms feel less predictable and less transparent. What you saw was never quite the same as what anyone else was seeing. You couldn’t count on a feed to work the same way from one month to the next. Just last week, Facebook implemented a new default Home tab on its app that prioritizes recommended content in the vein of TikTok, its main competitor.”