A paperback book is one with a thick paper or paperboard cover, often held together with glue, and bound with cardboard covered with cloth, leather, paper, or plastic. In contrast, hardcover books are bound with cardboard covered with more durable materials such as cloth or leather. Paperback editions are issued when a publisher decides to release a book in a low-cost format, and they tend to have smaller profit margins compared to hardcovers. They are also the preferred medium when a book is not expected to be a major seller, and they are differentiated by size, with "mass-market paperbacks" and larger "trade paperbacks" being common in the United States
. Paperback and hardcover books are both types of books, with paperbacks having a thin, cardstock-like cover, while hardcovers have a more durable cover
