A "codex" is an ancient manuscript in book form, typically made of parchment or paper. It consists of pages that are bound together, allowing for easier reading and storage compared to scrolls. Codices were widely used in the Roman Empire and later in the Middle Ages, serving as important carriers of texts, including religious, literary, and scientific works. The term "codex" can also refer to a specific collection of laws or rules, such as the Codex Justinianus, which compiled Roman law. Codices played a crucial role in the preservation and transmission of knowledge throughout history, influencing the development of modern books.