Nerdfighters are a community of fans who support the YouTube creators John Green and Hank Green. They are known for their enthusiasm for learning, creativity, and social activism. The term originated from the Green brothers' YouTube channel, Vlogbrothers, where they share educational content, personal stories, and discussions on various topics. The Nerdfighter community promotes the idea of "decreasing world suck," encouraging members to engage in charitable activities and positive social change. They often connect through social media, events like Nerdfighteria, and projects such as Project for Awesome, which raises funds for various charitable organizations.