A fan or supporter is someone who has an intense, occasionally overwhelming liking of a sporting club, person, group of persons, company, product, work of art, idea, or trend. Fans of a particular thing constitute its fanbase or fandom. They may start a fan club, hold fan conventions, create fanzines, write fan mail, or engage in similar activities.
In a few cases, individual fans may become so obsessed with the objects of their infatuation that they become fanboys/fangirls. These fans engage in behaviors that are considered extreme or abnormal. This includes idolatry or other forms of worship, such as creating a personal shrine dedicated to the idol at one’s home, and can sometimes extend to the point of the fans become stalkers.