Fun is the enjoyment of pleasure, particularly in leisure activities. Fun is an experience — short-term, often unexpected, informal, not cerebral and generally purposeless. It is an enjoyable distraction, diverting the mind and body from any serious task or contributing an extra dimension to it. Although particularly associated with recreation and play, fun may be encountered during work, social functions, and even seemingly mundane activities of daily living. It may often have little to no logical basis, and opinions on whether or not an activity is fun may differ. A distinction between enjoyment and fun is difficult but possible to articulate, fun being a more spontaneous, playful, or active event. There are psychological and physiological implications to the experience of fun.

Fun (stylized as fun.) is an American indie band based in New York City. It was formed by Nate Ruess, former lead singer of The Format, with Andrew Dost and Jack Antonoff, of Anathallo and Steel Train respectively. Fun has released two albums: Aim and Ignite in August 2009 and Some Nights in February 2012.