The bibliographical definition of an edition includes all copies of a book printed “from substantially the same setting of type,” including all minor typographical variants.

The numbering of book editions is a special case of the wider field of revision control. The traditional conventions for numbering book editions evolved spontaneously for several centuries before any greater applied science of revision control became important to humanity, which did not occur until the era of widespread computing had arrived (when software and electronic publishing came into existence). The old and new aspects of book edition numbering (from before and since the advent of computing) are discussed below.

According to the definition of edition above, a book printed today, by the same publisher, and from the same type as when it was first published, is still the first edition of that book to a bibliographer. However, book collectors generally use the term first edition to mean specifically the first print run of the first edition (aka "first edition, first impression"). Since World War II, books often include a number line (printers key) that indicates the print run.

A book is a set of written, printed, illustrated, or blank sheets, made of ink, paper, parchment, or other materials, usually fastened together to hinge at one side. A single sheet within a book is called a leaf, and each side of a leaf is called a page. A book produced in electronic format is known as an electronic book (e-book).

Books may also refer to works of literature, or a main division of such a work. In library and information science, a book is called a monograph, to distinguish it from serial periodicals such as magazines, journals or newspapers. The body of all written works including books is literature. In novels and sometimes other types of books (for example, biographies), a book may be divided into several large sections, also called books (Book 1, Book 2, Book 3, and so on). A lover of books is usually referred to as a bibliophile or, more informally, a bookworm.

A store where books are bought and sold is a bookstore or bookshop. Books can also be borrowed from libraries. In 2010, Google estimated that since the invention of printing, approximately 130,000,000 unique titles had been published.