Codex

A codex (from the Latin caudex for "trunk of a tree" or block of wood, book; plural codices) is a book constructed of a number of sheets of paper, vellum, papyrus, or similar materials, with hand-written content. The book is usually bound by stacking the pages and fixing one edge, and using a cover thicker than the sheets. Some codices are continuously folded like a concertina. The alternative to paged codex format for a long document is the continuous scroll. Examples of folded codices include the Maya codices. Sometimes people use the term for a book-style format, including modern printed books but excluding folded books.

The Romans developed the form from wooden writing tablets. The codex's gradual replacement of the scroll—the dominant book form in the ancient world—has been called the most important advance in book making before the invention of printing. The codex transformed the shape of the book itself, and offered a form that lasted for centuries. The spread of the codex is often associated with the rise of Christianity, which adopted the format for use with the Bible early on. First described by the 1st-century AD Roman poet Martial, who praised its convenient use, the codex achieved numerical parity with the scroll around AD 300, and had completely replaced it throughout the now Christianised Greco-Roman world by the 6th century.