Colleen Hoover was thrilled when her novel It Ends With Us suddenly shot to the top of The New York Times bestseller list late last year - and also a little bewildered. The book had come out four years before.
"You know at first, I didn't really know what was going on and even my publishers were like, why are we seeing an uptick in sales?" she recalls.
Hoover soon discovered that young readers were talking about her book on TiktTok, using the hashtag #BookTok, and Hoover had become a BookTok sensation.