Cover
(1) Generally, the outside of the book. (2) More commonly, the outside of a paperback, though note that a hardback also has a cover (or case), often protected by a jacket.
Before the industrial revolution, books were protected by covers made of leather, wood, ivory, etc. Even today, high-quality and/or prestigious books are bound in different types of leather. However, cloth drawn and glued onto stiff boards became the more common form of covering with industrialization and the explosion in book ownership in the nineteenth century.
Cloth is more durable than paper but the cloth-binding process is more involved and expensive. It was only in the 1930s, with the advent of mass-market publishing (modelled on high volumes and low prices), that the paperback emerged as a major rival to the hardback.
This definition is extracted (and expanded on) from the book Getting Published: A Companion for the Humanities and Social Sciences by Gerald Jackson and Marie Lenstrup. It was first referred to in the blog Getting Published in a post on the requirements and costs of self-publication.
