Steve Neale states that all genres contain instances of repetition and difference. He states that a film’s genre is defined by how much it conforms to the genre’s conventions, and how much it subverts from them. A film must have enough conventions to be seen as part of that genre, but must also differ enough so that it isn’t just a copy of existing films. He also says that popular cinema relies on audiences finding pleasure in repetition and difference.

Thomas Schatz states that the identifying feature of a film’s genre is its cultural contexts. He believes that there are two types of genre: genres of order and genres of integration. Genres of order focus on a typically male hero, who fights against a force of evil. Genres like action, gangster and western are generally genres of order. Genres of integration focus more on cooperation between people, and are often more domestic films. Genres such as romance, musicals and dramas tend to be genres of integration.

Christian Metz theorised that all genres go through a cycle of four stages in their life. They are the experimental stage, the classic stage, the parody stage, and the deconstruction stage. In the experimental stage, the foundations and generic conventions are established. In the classic stage, certain conventions become iconic and are recognisable from that genre. In the parody stage, people mock the established conventions as audiences recognise them. In the deconstruction stage, the genre can evolve and merge with others, and rules can be broken.

The War of the Worlds (dir. Byron Haskin, 1953), comes in the classic stage of the science-fiction genre’s cycle. When this film is released, the typical conventions of science-fiction have been established, and the film follows these. For example, the classic conventions of an alien invasion, a strong male hero and victory of the protagonists are all seen in The War of the Worlds. When The World’s End (dir. Edgar Wright, 2013) was released, the genre had moved into its deconstruction stage.