Little History
Codex? Basically a old name for a book.
The word codex comes from the Latin word caudex, meaning "trunk of a tree", “block of wood”.
The earliest fragments from codices that have survived come from Egypt, dated around the end of the 1st century or in the first half of the 2nd. Made with vellum, papyrus.
In the 6th century codices replaced the scrolls.