From Harry Potter to Star Wars, musicals to television shows, fandoms have been popping up for years, creating spaces where people can share their love of a book, film, person or even a brand.
More businesses are seeing the value of tapping into fandoms. Even the quickest walk through Heathrow Airport in London, and the enormous Harry Potter store, will show just how profitable a fandom can be, but for many businesses, it's also a way to build a community among their customers.
David Meerman Scott, an entrepreneur and strategist, has become a fan of fandoms, so to speak, as his new book Fanocracy - co-written with his daughter, Reiko - delves into how to how to "turn fans into customers and customers into fans".
Taking to the stage at Pendulum Summit in Dublin's Convention Centre, the author spoke about how building a fandom is one route to a more authentic connection with customers.
By tapping into the things he and Reiko are fans of - music for him, Harry Potter for her - he explores how people have responded to the tribe they find in fandoms. He speaks about how one United States Government agency has "millions of fans", an incredible feat until you realise he's talking about Nasa and that you, most likely, are one of those millions.
Having earned a neuroscience degree from Columbia University, Reiko - who is now a medical student at Boston University - was the perfect writing partner, as in her spare time she writes and publishes fanfiction based on her favorite fantasy worlds and loves to cosplay at Comic Con.
We caught up with the author and strategist at the Pendulum Summit to find out more about the appeal of fandoms - watch it above.