How were books bound?

When a collection of written pages were bound together to form a codex – the earliest form of a book – the craft of bookbinding was invented. By this definition, one of the oldest known books in the world is a 2,500-year-old, six-page volume written in Etruscan (the now-dead language of a pre-Roman Italian civilisation).
With the rise in demand for the Christian Bible, the creation of large books began to gain popularity. From the 5th century up until the Middle Ages, books were often bound using a vellum (finely scraped animal hide) writing surface with flat spines and wooden covers, secured with clasps to stop humidity from warping its shape.
The vellum was placed together in several folded sheets to form a group of up to eight pages called an octavo section. As a section, these pages would be more resilient to tearing when sewn together. They were then sandwiched between wooden panels and covered with the material of the bookbinder’s choice: cloth, leather or even gemstones and ivory for more wealthy clients. More gorily, during the Dark Ages and early medieval times, it wasn’t uncommon to encounter books that were bound in human skin!