The most common trim sizes for fiction and nonfiction are known as "trade" and "digest." The most common trim sizes for children's books are known as "letter," "square," and "landscape." It's up to you to decide on which size works best for your project and genre. Our recommended book trim sizes and binding options can be found here. When it comes to paper stock, you have two options: uncoated or coated. Uncoated paper has a natural feel and is great for traditional books without imagery. In contrast, coated paper is best suited for photography, art, comic, and children's books.