There are roughly about 500 known books bound in human skin, but this number is growing as existing collections of such books are explored. This practice of bookbinding, known as anthropodermic bibliopegy, began in the 16th and 17th centuries, primarily for legal and scientific texts. It was seen as a way to ensure the longevity of important texts as well as a way of honoring the authors.
Today, some of these bound books are held by universities, libraries, and museums in the United States, the United Kingdom, France, Germany, and elsewhere.
Typically, the practice of anthropodermic bibliopegy required pieces of skin or whole skins to be removed from cadavers. Pieces of preserved skin were dried and treated before being used to bind books. It’s thought that this practice may have also been used in cases of torture and execution prior to other bookbinding methods becoming more readily used.
Museums, libraries and universities today take steps to preserve and protect these books. While some may be available for viewing, libraries and museums take extra care to monitor and control their environment in order to reduce the risk of the bindings degrading due to natural causes. The bookbinding material must also be verified by an expert in order to determine if the material is human or not.
If you’re interested in learning more about these unique books and the process of anthropodermic bibliopegy, here’s a great article from the Smithsonian Magazine with additional information: https://www.smithsonianmag.com/smart-news/500-books-are-bound-human-skin-180949620/
I hope this helps to answer your question.