Any shelving area in a library to which users have unrestricted access. Synonymous with open access. Compare with closed stacks. The benefit is that library users may research and browse without staff supervision, but a drawback is that some will misplace items or leave the shelves in disorder. Thievery may also be an issue, especially with coveted DVD collections. Library staff can perform periodic shelf reading and blocking (aligning the books with the edges of the shelves) to keep the collection orderly.