NEW YORK • When Christine Riccio was a teenager growing up in New Jersey, she and her sister would upload videos to YouTube of the two of them being silly, dancing to Britney Spears' Piece Of Me or attempting a back flip.
It was not until Riccio was in college in 2010 that she "actually talked to the camera" for the first time and decided to upload a video book review of Suzanne Collins' The Hunger Games (2008).
"I was reading a lot of books and I had no one to discuss them with," she said, explaining why she turned to the Internet. "I was like, 'I'll be lucky if I ever get 500 subscribers over here.'"
Initially, Riccio split her content onto two channels, one for comedy and another for books. But after college, while interning at actor Will Ferrell's production company in California in 2012, she - like many interns - had a lot of free time on her hands.
She read and came up with video ideas for her book channel, PolandBananasBooks and began uploading skits, reactions to book-to-movie adaptations and book hauls (in Internet parlance, a haul is when someone shares the items he has bought during a shopping spree).
Her book channel grew from fewer than 1,000 to 5,000 subscribers that summer.
Now at the age of 27, with close to 400,000 subscribers, she is YouTube's most popular "BookTuber", chronicling books for a largely millennial and teenage audience.
That Riccio and other BookTubers' audience skews younger is significant, given that it allows publishers to tap a market that may not necessarily look to traditional publications for recommendations.
Ms Erica Barmash, marketing director for the children's imprint at Bloomsbury, has worked with Riccio on several campaigns and said her channel helps them target teens by "going after them where they already are", on YouTube.
BookTubers may be small fish at events like VidCon - a yearly conference in Anaheim, California, that brings together creators and subscribers of online videos - but in the book world, they are celebrities.
At conferences like BookCon or YALLFest, a young adult literary festival, "everyone we see is a subscriber", Riccio said. "We get stopped all the time."
A panel at BookCon in May was attended by almost 700 people.
Ms Brittany Kaback, who works for a boutique marketing agency called Big Honcho Media, which connects publishing companies with "influencers", called the BookTubers "hugely influential".
"I think for a lot of the people who are into watching BookTube videos, it feels like taking a recommendation from a friend," Ms Kaback said.
As a result, BookTubers are sent advance copies of upcoming books to feature and publishing houses often sponsor their videos to promote new releases.
Though their influence is hard to quantify, Ms Kaback said viewer engagement is substantial. Many subscribers comment that they were persuaded to buy the book being promoted.
According to YouTube, the community as a whole has got more than 200 million views and, compared with this time last year, engagement with them is up 40 per cent.
While the biggest BookTubers like Riccio tend to focus on young adult literature, there is also a smaller subsection of creators whose content centres on adult literature, both classic and contemporary.
One, Dominique Taylor, said that her aspiration for her channel, The Storyscape, is for it to become "a literary teaching hub".
BookTubers discuss character development, themes and motifs, she said, and "that's English class, essentially".
Ariel Bissett, one of the BookTubers Riccio met at VidCon in 2013 and with whom she has collaborated, echoed Taylor's sentiments in a recent video in which she discussed BookTube's role in relation to the classroom.
She calls BookTube "a haven for people who never felt cool or popular with their reading" and said it teaches "passion and love" for books.
Riccio and Jesse George, another prominent BookTuber, agree. "That's the thing about BookTube," said George. "If you're not a big reader, it inspires you to become one."