If you're a book-obsessed social media user, odds are you have a Tumblr account — one that's probably filled with bookshelfies, fan art, fan-fiction, book theories, pictures of adorable animals ...

As a platform, Tumblr is a godsend for niche fandoms.So launching the company’s first official book club with a novel called “Fangirl” is an especially appropriate move for the blogging service.

Tumblr already has both a large audience of teens and a vibrant book community, said Rachel Fershleiser, head of publishing outreach for the microblogging platform.