Page proof. This is a preliminary copy of the final layout of a book. It will show the layout of the pages and placement of any illustrations, charts, etc. The publisher's editorial staff will check the page proofs carefully for any errors, and depending on the terms of the contract, the author will also be asked to check them for errors. If given the opportunity, the author needs to take this task very seriously. Although they know the editors are also checking it, in some cases the author is the only one who will recognize if something is missing or out of order. When the page proofs are sent, the editor will indicate how long the author has to check and return them. If they are not returned on time, the contract will usually indicate that the publisher can assume they are correct and move ahead with printing the book. Realize that this is not the stage where the author can be asking for major changes, such as adding or deleting material, or rearranging the chapters. Changes at this stage are expensive, and most contracts indicate that if you ask for more than the correction of errors, you will be charged for such changes. The following Website gives detailed instructions on how to review the page proofs. http://www.wiley.com/WileyCDA/Section/id-302991.html.