A film genre is a motion picture category based on similarities in either the emotional response to the film (namely, tragic, comic, etc.) or the narrative elements. Most theories of film genre are borrowed from the literary world. The basic genres include fiction and documentary, from which subgenres have emerged, such as docudrama. Other subgenres include the courtroom and trial-focused drama known as the legal drama. Types of fiction which may seem unrelated can also be combined to form hybrid subgenres, such as the melding of horror and comedy such as in the Shaun of the Dead. Other popular combinations are the romantic comedy and the action comedy film.
Steve Neale’s theory of Repetition and Difference. Steve Neale states that genres all contain instances of repetition and difference, difference is essential to the to the economy of the genre.
Neale states that the film and it’s genre is defined by two things:
How much is conforms to its genre’s individual conventions and stereotypes. A film must match the genre’s conventions to be identified as part of that genre.
How much a film subverts the genre’s conventions and stereotypes. The film must subvert convention enough to be considered unique and not just a clone of an existing film.
Neale states that Hollywood’s generic regime performs two functions:
To guarantee pleasure and meaning for the audience.
To offset financial risks of film production by providing collateral against innovation and difference.
Popular cinema relies on audiences finding pleasure in difference and repetition i.e. recognition of familiar elements and the way those elements are linked in an unfamiliar way or the way that unfamiliar elements might be introduced.
Genre is constituted by specific systems of expectations and hypothesis which spectators bring with them to the cinema and which and which interact with the films themselves during the course of the viewing process.
To the film’s production team (producer, director etc) genre provides a template.
To the film’s distributors genre provides assumptions about which audiences they should be marketing to.
To the film’s audience genre identifies a liked of disliked formula and provides certain rules of engagement in terms of anticipation of enjoyment.
The video below explains Steve Neale's theories in more detail.