Nonfiction books can be a little easier to narrow down than fiction ones. Most popular nonfiction books are histories or biographies of famous people. Is there a famous person you'd like to know more about? Do you want to know more about a country, a landmark, a war, a historical event? Do you want to know more about oceans, or dinosaurs, or pirates, or stage magic? Pretty much anything you can think of has had a nonfiction book written about it.