Tom Ryall's genre theory proposes that genres provide a framework of rules that guide filmmakers' production and audiences' interpretation. These conventions fall within four categories: iconography, narrative structure, character representations, and underlying ideological themes. Ryall also developed a triangular model examining the relationships between industry, text, and subject. He argues genres should be analyzed considering how they affect audiences through emotions like fear or laughter. Ryall additionally provides a list of categories he considers true film genres such as westerns, horror films, and comedies.