Before books were stored in libraries, they were kept face down in cupboards, on shelves or in chests. While our modern organizational system did not exist in the Middle Ages, books were kept together in categories, separated from those on different subjects. During the evolution of libraries, books began to be stored upright. However, they were placed on shelves with the spine facing inwards, the title being written on outward-facing page edges or on slips of paper inserted into the book. After the books were organized into their respective categories, each book would be given a shelfmark indicating the exact cupboard and shelf on which the book belonged, and sometimes the precise position of the book on the shelf. Some libraries also chained their books to shelves or desks as a preventative measure, so that the reader could not take the book from the library, but must stay in place to read it.

Up until the end of the Middle Ages, most libraries were exclusively in monasteries. However, by the late Middle Ages, libraries began to appear in Cathedral schools and universities, and in the homes of scholars and wealthy aristocrats.