A codex (Latin for block of wood, book; plural codices) is a book in the format used for modern books, with separate pages normally bound together and given a cover. Developed by the Romans from wooden writing tablets, its gradual replacement of the scroll, the dominant form of book in the ancient world, has been termed the most important advance in the history of the book prior to the invention of printing. The spread of the codex is closely associated with the rise of Christianity which has been using it as the exclusive book format of the Bible almost from the beginning.
