The outside of a book requires a lot of planning. While it may not seem like much — just a front cover, back cover, and spine — this could very well be one of the most complicated elements of the book. The cover is what people are going to see first. If they don't like the looks of the cover, chances are they won't bother finding out what's inside. The cover is one of the primary selling tools of the book. It must be perfect.
The company will probably decide to publish your book in hardcover first. Sometimes a hardcover book won't have anything at all printed on the front and back covers. The spine will have the title of the book, the author's name, and the publisher's name. This is common in adult books. Children's books, however, will sometimes print the same design from the jacket directly on the hardcover.
A jacket will cover the hardcover, adding extra protection. For the prices we pay for hardcovers, we certainly should get a little more. The front of the jacket will have a design that identifies the book, the title, the author's name, the illustrator's name, and mention of any awards the book may have won. The front flap of the jacket will contain promotional copy, usually giving a brief description of the plot, and sometimes the back flap will contain the author's and illustrator's bios. The back of the jacket will include the ISBN, bar code, and price, and sometimes the publisher's name. You will occasionally find some promotional copy on the back of the jacket, such as quotes of praise the book has received. These might be excerpts from reviews, or blurbs contributed by writers in the field.
Paperback covers include the same information you find on a hardcover's jacket, but it's printed directly on the cover. If a publishing company prints a paperback edition following a hardcover edition, the covers of these two books may or may not be the same.