What is genre theory?

Genre theory revolves around the ideas surrounding how we define and distinguish genres, and how we categorise films into genres based on usually conventional factors. Genre will often be divided by observing characteristic features exhibited within a film, using recurring symbols and motifs within the film to place it within a genre. When it comes to categorising films into genres, often one will look to the characters, settings, the plot, sounds and star persona, and even technical elements such as specific camera shots, cinematography, and styles of editing; the same way an audience might have expectations from a specific director, they will also have expectations for a film based on its designated genre. Ultimately, one can see how genre is often used by filmmakers and studios to create expectation from its target audience - genre can be used as a tool to communicate to the audience what the film will contain. However, when it comes to creating films using this same set of rules and conventions, boredom will always factor in as it does when repetition occurs. What film studios can do is use genre - familiarity - as a tool to grab audience attention, and then incorporate the new and/or unfamiliar into the film, as genre indicates pleasure to the audience. An audience member might not see a musical film due to their preferences and believing they cannot derive pleasure from seeing such a film. A filmmaker may create a film of a different genre but may incorporate a scene where the characters sing as they would in a musical, and it would be refreshing, enjoyable, and pleasurable to the audience member. What this also indicates is that genre classification can very well be a limiting thing, and we must acknowledge that no genre can reserve a theme, symbol, or feature for itself as they can be found across a wide variety of media, regardless of genre. This is also known as hybridism.
Genre theory also questions how we define genre, and whether it is in fact limiting and generalising. One will ask whether genre is ultimately defined by audience expectation, when someone else might propose that genre means something different between different people and bodies; genre means something different to the audience than it does to the distributors, than it does to producers. We have to understand that even if we wish to define genres clearly, that it is fluid in its nature and revisionism will occur, as it has in the past, often due to sociological factors and changes in traditional ideology. Perhaps this in itself is proof enough that genre cannot be easily defined, and is to an extent, subjective. However, these decisions are made based on specific iconography within films, and this in turn cannot be ignored. According to Rick Altman, there are two ways to define a genre - an inclusive or semantic way, and an exclusive or syntactic way. A semantic approach will be concerned with the conventions, surface-level elements and narrative tropes of the film, while a syntactic approach asks us to observe closely the relationships between these elements and the narrative of the film. Altman even suggests a third approach which acknowledges the wider societal context of films, that they exist in an industry which aims to cater to audiences, ultimately, for the goal of profit and audience gratification. Altman, and many other theorists, help us understand and acknowledge the consequences of defining genre and what it means not just for film, but for audiences and the film industry.