A comedy film is a category of film in which the main emphasis is on humor. These films are designed to make the audience laugh through amusement and most often work by exaggerating characteristics for humorous effect. Films in this style traditionally have a happy ending (black comedy being an exception). One of the oldest genres in film—and derived from the classical comedy in theatre—some of the earliest silent films were comedies, as slapstick comedy often relies on visual depictions, without requiring sound. When sound films became more prevalent during the 1920s, comedy films took another swing, as laughter could result from burlesque situations but also dialogue.