Endsheets, also known as endpapers or endleaves, are the pages at the beginning and end of many hardcover books. They are used to glue the inside pages, known as the book block, to the hardcover, known as the case.
Endsheets are usually made from a separate, uncoated paper stock slightly heavier than the paper used for the inside pages. Typically, endsheets are either left blank, printed with a solid color, or printed with a pattern.
Important Design Consideration
When designing your endsheets, keep in mind that on the pages where the endsheets meet the inside pages the innermost 10mm will be glued together. Thus, these pages are not well suited for spreads or designs that span both pages.