Genre is the term for any category of literature or other forms of art or entertainment, e.g. music, whether written or spoken, audial or visual, based on some set of stylistic criteria. Genres are formed by conventions that change over time as new genres are invented and the use of old ones are discontinued. Often, works fit into multiple genres by way of borrowing and recombining these conventions.

In film theory, genre refers to the method based on similarities in the narrative elements from which films are constructed. Most theories of film genre are borrowed from literary genre criticism. Besides the basic distinction in genre between fiction and documentary , film genres can be categorized in several ways.

The setting is the milieu or environment where the story and action takes place. The theme or topic refers to the issues or concepts that the film revolves around. The mood is the emotional tone of the film. Format refers to the way the film was shot (e.g., anamorphic widescreen) or the manner of presentation (e.g.: 35 mm, 16 mm or 8 mm). An additional way of categorizing film genres is by the target audience.

Film genres often branch out into subgenres, as in the case of the courtroom and trial-focused subgenre of drama known as the legal drama. They can be combined to form hybrid genres, such as the melding of horror and comedy in the Evil Dead films.