Book Genres

So, you've decided to write a book, but you don't know what to write. Maybe you want to write something you like, or something you think other people will like and want to read. Here's a crash course in book genres!
My personal favorite; fantasy. Magic, other worlds, battles, stuff like that. If it deals with spells, witches, dragons, or princess getting abducted by dragons, chances are it's a fantasy novel.
Science Fiction; aliens, other planets, phasers and lightsabers (copyright alert!) and time travel. This one can be a little confusing to write, especially if you go with time travel. Superheroes also fall into this category.
Horror: The soul purpose of frightening somebody. Scaring them out of their mind, or making them think twice. It can be psychological or frightening. Two good examples of horror would be Alfred Hitchcock and the Twilight Zone, as well as almost all of Stephen King's books.
Mystery: Murders, robberies, smugglers, kidnappers...if you have someone trying to solve a crime, that's a mystery! Make sure you have the criminal picked out beforehand; this genre may require the most planning ahead of all of them. A good example of mysteries would be The Hardy Boys or Perry Mason.
Romance: Romance is one of my person least-favorite genres, but it's extremely popular. Anything about a person falling for another, or being torn by two different people (the often-spoken-of "love triangle") or just loving someone else. There must be someone loving somebody! Otherwise it wouldn't be a romance... can't give you any examples. Just look at your local bookstore and there will probably be hundreds with muscular men holding beautiful women in their arms on the covers.
Humor: Slapstick, witty, or just totally ridiculous, this is the comedy genre. Something just intended to make somebody laugh. Perhaps one of the hardest genres to write. Can't give you any examples for this one.
Spiritual: Meant to inspire you with religious themes. Can't give you any examples for this one either. I'm a Christian, certainly, but I can't think of any right now.
Historical Fiction: Anything based off of History at any time or place. Must have some facts and historical things. You can invent some things--it's fiction for a reason--but there has to be some truth in your story. Gone With the Wind is an example for this.
Non-fiction: nothing can be made up. Must be entirely fact, and can't have anything false in it. Biographies, stuff like that are non-fiction.
Well, this has been a quick run-through of popular book genres! Hopefully now you know what genre to write!