Fan communities play a significant role in the popularity of a series by fostering a sense of belonging, creating a space for fans to discuss, analyze, and celebrate the series, and generating buzz and excitement through fan theories, fan art, fan fiction, and other fan-generated content. These communities help keep the series relevant, attract new fans, and maintain interest during hiatuses or between releases. Overall, fan communities can contribute to the longevity and success of a series by building a dedicated and enthusiastic fan base.