Many of this year’s bestselling books have something in common, but it’s not any of the usual factors: a famous or long-established author, a tie-in with a movie or TV show.

It is TikTok.

Early last year, the publishing industry began to notice that the books readers were gushing about on TikTok - the social media platform that traffics in short videos - were showing up on bestseller lists. Publishers were surprised, authors were surprised, even the readers making those TikTok videos were surprised.