The document discusses horror subgenres and hybrid genres. It defines a subgenre as a category of works that forms a specific class within a larger genre. Some of the main horror subgenres mentioned are comedy horror, slasher films, supernatural horror films, and extraterrestrial horror films. It then defines a hybrid genre as a combination of two different genres, providing examples of horror-western and horror-sci-fi hybrids like Deadlands and Alien respectively.