Subgenres

A genre is often broken down into subgenres. For example, there are more than a hundred subgenres of romance.

Genre fiction defies any classification scheme you try to impose on it though. That's because classifying novels is like classifying living things: since they evolve, they don't fit neatly into artificial categories superimposed on their evolutionary tree. Therefore, just as you find animals that are intermediate forms, you find genre novels classed as belonging to more than one subgenre.

Fantasy fiction, science fiction, and westerns are principally milieu stories.

Mysteries are idea stories that have evolved into two main branches that don't seem related. But they are. They are idea stories that pose some question or problem to be solved. Suspense fiction evolved from earlier mystery fiction as a subgenre that carries the suspense in that question or problem beyond mere curiosity into maximum anxiety and apprehension. So, today mystery fiction has two main branches: crime fiction and suspense. Crime fiction includes the classic English whodunit, the American detective novel, caper stories, and so on. Suspense fiction includes psychological thrillers, spy fiction, techno-thrillers, and so forth.

But the classification of genre fiction ramifies into many more-specific categories. Crime fiction, for example, may be classed as hard-boiled, soft-boiled, innocent-at-risk, or comic — to name just a few of the many possibilities.

Some novels are hybrids. For example, a story that takes place in space ship or on another planet could be an idea story, not strictly a milieu story. The spaceship might be disabled, or the local star might be about to go nova. Then you have a problem to solve, as in a caper story. What is this novel? science fiction? or a subgenre of mystery? We will surely call it science fiction, but it isn't pure science fiction.