Types

                                    Smaller libraries can sometimes be found in private homes.        

Libraries can be divided into categories by several methods:
By the entity (institution, municipality, or corporate body) that supports or perpetuates them
academic libraries
corporate libraries
government libraries, such as national libraries
historical society libraries
private libraries
public libraries
school libraries
special libraries
By the type of documents or materials they hold
data libraries
digital libraries
map libraries or collections
picture (photograph) libraries
slide libraries
tool libraries
By the subject matter of documents they hold
architecture libraries
fine arts libraries
law libraries
medical libraries
aquatic science libraries
theological libraries
By the users they serve
military communities
users who are blind or visually/physically handicapped (see National Library Service for the Blind and Physically Handicapped)
prisons
By traditional professional divisions
Academic libraries — These libraries are located on the campuses of colleges and universities and serve primarily the students and faculty of that and other academic institutions. Some academic libraries, especially those at public institutions, are accessible to members of the general public in whole or in part.
Public libraries or public lending libraries — These libraries provide service to the general public and make at least some of their books available for borrowing, so that readers may use them at home over a period of days or weeks. Typically, libraries issue library cards to community members wishing to borrow books. Many public libraries also serve as community organizations that provide free services and events to the public, such as reading groups and toddler story time.
Research libraries — These libraries are intended for supporting scholarly research, and therefore maintain permanent collections and attempt to provide access to all necessary material. Research libraries are most often academic libraries or national libraries, but many large special libraries have research libraries within their special field and a very few of the largest public libraries also serve as research libraries.
School libraries — Most public and private primary and secondary schools have libraries designed to support the school's curriculum.
Special libraries — All other libraries fall into this category. Many private businesses and public organizations, including hospitals, museums, research laboratories, law firms, and many government departments and agencies, maintain their own libraries for the use of their employees in doing specialized research related to their work. Special libraries may or may not be accessible to some identified part of the general public. Branches of a large academic or research libraries dealing with particular subjects are also usually called "special libraries": they are generally associated with one or more academic departments. Special libraries are distinguished from special collections, which are branches or parts of a library intended for rare books, manuscripts, and similar material.

Many institutions make a distinction between circulating libraries (where materials are expected and intended to be loaned to patrons, institutions, or other libraries) and collecting libraries (where the materials are selected on a basis of their natures or subject matter). Many modern libraries are a mixture of both, as they contain a general collection for circulation, and a reference collection which is often more specialized, as well as restricted to the library premises.

A cabinet of books in the Tian Yi Chamber, the oldest extant library in China, dating to 1561.