What is a genre? A genre is category, type, or class of literature. Sounds simple enough but in reality is complicated and can be confusing for the writer and, perhaps, even for the reader.
Classifying genres starts out simply enough: Fiction and Nonfiction.
Within fiction, the broad categories are:
Drama
Tragedy
Comedy
Tragicomedy
Ahhh, but let’s add more like it was seven-layer dip.
Fiction has the following sub-genres:
Adventure
Romance
Crime
Mystery
Fantasy
Fiction Narrative
Fiction in Verse
Historical Fiction
Horror
Humor
Poetry
Realistic Fiction
Literary Fiction
Science Fiction
Westerns
But wait! There’s more! Let’s get more sub-sub genres within fiction.
This is an extremely small list:
Absurdist
Men’s Adventure
Children’s Literature
Romantic Comedy
Parody
Black Comedy
Experimental
Erotica
Historical
Historical Romance
Regency Romance
Literary
Metafiction
Philosophical
Political Satire
Pulp
Religious
Family Saga
Speculative
Steampunk
Cyberpunk
Dystopian
Alternative History
Paranormal
Monster Literature
Supernatural
Comic Fantasy
Dark Fantasy
High Fantasy
Historical Fantasy
Low Fantasy
Urban Fantasy
Crime
Detective
Chick-Lit
Melodrama
Legal Thriller
Medical Thriller
Political Thriller
You get the idea. And this isn’t including works that borrow from multiple genres.
Within nonfiction, the broad categories are:
Biography/Autobiography
Essay
Speech
Textbooks
And here comes the sub-genres within nonfiction:
Creative nonfiction
Memoir
Diaries and Journals
History
Letters
Religious text
Clearly, nonfiction is less taxing to classify.
As readers, we tend to gravitate towards one type of book over another, one author over another. But what happens when your favorite author wants to expand and try a different genre out? One of my favorite authors, Ken Follett, has written a nonfiction book On Wings of Eagles about Ross Perot’s involvement in retrieving two of his employees who had been falsely arrested during a revolution in Tehran, Iran back in the late 1970s. Follett is most well-known for historical fiction set during WWII and the Middle Ages but has written more modern novels such as Paper Money (written under a pseudonym in the 1970s) and The Hammer of Eden. Naturally when an author becomes extremely well-known, their publisher isn’t as concerned about how to market the book. All they have to say is ‘New book from Big Famous Author XYZ’ and fans will buy it.
Our reasons are as varied as the types of books available and book publishers know this. Genre classifications allow book publishers to know how to market a book to the correct audience.
But what about books that cross genres? A book that spans several generations, for example. Say it starts off during the American Revolution and ends with the family as it is today. Is that considered historical fiction or just general fiction? Is it a percentage of the content of the book that determines the dominate genre? The job of making this determination is usually left to the marketing department of a book publishing company however, if you are self-publishing, you generally have a good idea what category your work falls into.
So do genre classifications help or hinder a writer’s creativity? Worrying about what neat little box one’s work falls into while writing it can only hinder. And bring up the dreaded writers gremlin salivating on your shoulder as it peers down on your work, ready to pick the story apart. Let the words, characters, settings, and plots flow. Get it down onto paper or computer screen and don’t worry about its box until the time comes to publish it.
I personally am interested in writing historical fiction; it’s what I love to read the most and I have a lot of fun doing the research. But a lot of story ideas I’ve jotted down aren’t historical fiction. I love to read different types of books and authors, so why should I limit myself to one particular genre? The characters drive the piece not sitting around fretting about what genre the story fits.
DH Hanni 
There was a time when I classified books as fiction or non-fiction. The scary stuff was horror. The sexy stuff was romance. The stuff that couldn’t ever be real was fantasy. The stuff with gadgets and futuristic stuff was science fiction. The end. Now there are so many genres to choose from! In many, many ways, this is a good thing. As a reader, it narrows down those huge lists of choices so that we’re only looking for the books that truly interest us. But as an author….omg! There are too many choices, lol!
I know I tend to lean towards certain types of fiction (love women heroes, stories about the underdog winning, books that make me cry, love stories, stories with quirky characters…) and steer away from certain types of fiction (stuff that will give me nightmares, or that detail torture or that make sexuality into something ugly). But as a writer, the list of available genres can be highly overwhelming!