A chained library is a library where the books are attached to their bookcase by a chain, which is sufficiently long enough to allow the books to be taken from their shelves and read, but not removed from the library itself. This would prevent theft of the library's materials.[1] However, it also led to crowding and awkwardness when readers had to stand side by side, each holding a book or clumping so they could share one.[2] The practice was usual for reference libraries (that is, the vast majority of libraries) from the Middle Ages to around the 18th century.