The Seattle International Film Festival (SIFF) is a film festival held annually in Seattle, Washington, United States since 1976. It usually takes place in late May and/or early June. It is one of the largest festivals in the world, and features a diverse assortment of predominantly independent and foreign films, and a strong contingent of documentaries.

A film festival is an organized, extended presentation of films in one or more cinemas or screening venues, usually in a single city or region. Increasingly, film festivals show some films outdoors. Films may be of recent date and depending upon the festival's focus, can include International and Domestic releases. Some film festivals focus on a specific filmmaker, genre of film, or subject matter. Several film festivals focus solely on presenting short films of a defined maximum length. Film festivals are typically annual events. Some film historians, including Jerry Beck, do not consider film festivals as official releases of the film.