A library is a space which houses large collections of books with supplementary areas for their use in study, research, or recreational reading. Small libraries associated with hospitals, prisons, secondary schools, law firms, and other such institutions are not listed as libraries.

Most libraries can be categorized as public, private, or educational; any library which falls under this unspecified library usage has not yet been assigned to the proper category.

Use of the collection distinguishes library space from storage devoted primarily to preserving media for possible future reference. That preservation purpose belongs to an archive. Public access alone does not determine whether a library is public, private, or educational.