The document discusses the definition and changes of genres in film. It notes that genres are difficult to define strictly and often involve influences from multiple genres, making them hybrids. While certain conventions are commonly associated with genres, like settings for horror films, genres are not rigid categories. This is exemplified through the analysis of the short film "Across The Hall," which has elements of both thriller and romance genres. Genre is important for both film producers and audiences to understand the key elements and target audiences.