A codex is a book in the format used for modern books, with multiple quires or gatherings (sheets of paper

Paper

Paper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....

 or vellum

Vellum

Vellum is mammal skin prepared for writing or printing on, to produce single pages, scrolls, codices or books. It is generally smooth and durable, although there are great variations depending on preparation, the quality of the skin and the type of animal used...

 in multiples of two which are folded and stitched through) typically bound

Bookbinding

Bookbinding is the process of physically assembling a book from a number of folded or unfolded sheets of paper or other material. It usually involves attaching covers to the resulting text-block.-Origins of the book:...

 together and given a cover.

Developed by the Romans

Ancient Rome

Ancient Rome was a thriving civilization that grew on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to one of the largest empires in the ancient world....

 from wooden writing tablets

Wax tablet

A wax tablet is a tablet made of wood and covered with a layer of wax, often linked loosely to a cover tablet, as a "double-leaved" diptych. It was used as a reusable and portable writing surface in Antiquity and throughout the Middle Ages...

, its gradual replacement of the scroll

Scroll

A scroll is a roll of parchment, papyrus, or paper, which has been drawn or written upon.Scroll may also refer to:*Scroll , the decoratively curved end of the pegbox of string instruments such as violins...

, the dominant form of book in the ancient world

Classical antiquity

Classical antiquity is a broad term for a long period of cultural history centered on the Mediterranean Sea, comprising the interlocking civilizations of ancient Greece and ancient Rome, collectively known as the Greco-Roman world...

, has been termed the most important advance in the history of the book prior to the invention of printing

Printing press

A printing press is a device for applying pressure to an inked surface resting upon a print medium , thereby transferring the ink...

.