From looking at various books, I have researched the meaning of genre and discovered some of the issues with generalising films, but also the importance of audience members being able to identify with genre.
The parts I've underlined are the most important points I've picked out.
The page above explores the meaning of genre and the basic conventions used to create a film in a certain genre.
As we see in the pages above, the main problems with putting films into specific genres is the overlap of conventions. Although many films fit mostly into a specific genre, there will be elements from other genres in most films, and also, not every film in a genre will follow all of the same conventions. It is hard to define the genre of a film because of this, as each film is different. Film marketers will use genre conventions to target a certain demographic, and will mostly market it as just one genre. Generally, a film will include many conventions of a certain genre, or conventions that apply to most genres.
We also see the history of genres. As film develops, as do genres and conventions. Film-makers and marketers tend to adapt to these changes. More and more subgenres are being created and different types of films are being made all the time. When this happens, films will sometimes be marketed as cross genre, which promotes the film to different demographics and audiences.
The pages of this other book further define genre and its meaning, along with tackling the problems of categorising films, and goes into a more detailed explaination of the types of conventions used by film-makers to fit a film into the intended genre.