Remaindered books or remainders are printed books that are no longer selling well, and whose remaining unsold copies are liquidated by the publisher at greatly reduced prices. While the publisher may take a net loss on the sales of these books, they are able to recover at least some of their sunken costs on the sale and clear out space in the warehouses.
Copies of remaindered books may be marked by the publisher, distributor, or bookseller to prevent them from being returned. "Remainder marks" have varied over the years, but today most remainders are marked with a stroke with a felt-tipped marker across the top or bottom of the book's pages, near the spine.
Only hardcovers and trade paperbacks (paperback books, often larger than "pocket" paperbacks, sold "to the trade" or directly to sales outlets) are typically remaindered. Mass market paperbacks ("pocket" paperback books sold through a third-party distributor) usually become stripped books rather than remaindered books.