I.

Introduction

Library (institution), collection of books and other informational materials made available to people for reading, study, or reference. The word library comes from liber, the Latin word for “book.” However, library collections have almost always contained a variety of materials. Contemporary libraries maintain collections that include not only printed materials such as manuscripts, books, newspapers, and magazines, but also art reproductions, films, sound and video recordings, maps, photographs, microfiches, CD-ROMs, computer software, online databases, and other media. In addition to maintaining collections within library buildings, modern libraries often feature telecommunications links that provide users with access to information at remote sites.

The central mission of a library is to collect, organize, preserve, and provide access to knowledge and information. In fulfilling this mission, libraries preserve a valuable record of culture that can be passed down to succeeding generations. Libraries are an essential link in this communication between the past, present, and future. Whether the cultural record is contained in books or in electronic formats, libraries ensure that the record is preserved and made available for later use. Libraries provide people with access to the information they need to work, play, learn, and govern.

People in many professions use library resources to assist them in their work. People also use library resources to gain information about personal interests or to obtain recreational materials such as films and novels. Students use libraries to supplement and enhance their classroom experiences, to learn skills in locating sources of information, and to develop good reading and study habits. Public officials use libraries to research legislation and public policy issues. One of the most valued of all cultural institutions, the library provides information and services that are essential to learning and progress.

This article provides an overview of the different types of libraries and explains in detail their various collections, functions, and services. It also profiles careers in library work, the education of librarians, and several professional organizations for librarians. Other sections of the article trace the history of libraries, from their origins in the ancient world through the end of the 20th century and the major trends and challenges facing libraries today. Finally, the article describes contemporary library systems in countries throughout the world.

II.

Types of Libraries

Because no single library can contain the information sought by every potential user, different types of libraries exist to serve different needs. Libraries fall into six basic categories: (1) public libraries, which serve all members of the general public; (2) school libraries, which serve students and faculty through the high school level; (3) college and university libraries, which serve students and faculty in higher education; (4) research libraries, which serve the needs of advanced scholars; (5) special libraries, which serve various organizations, industries, and governmental agencies; and (6) government libraries, which serve governmental departments and agencies, and often the general public as well. Each type of library develops its mission statement, collections, services, and facilities to satisfy the needs of its particular clientele.

In the United States, there are more than 130,000 libraries of all types. School libraries account for the majority of libraries in the United States, totaling about 100,000. The United States also has about 16,000 public libraries, including both central and branch libraries. Canada maintains more than 3,700 central and branch public libraries.

Libraries of all types generally form networks with other libraries, through which they share resources, information, technology, and staff expertise. Most libraries exist as autonomous institutions, but nearly all libraries also form parts of larger regional, national, or even international library networks. These links between institutions ensure that a library’s users can obtain needed information quickly and usually free of charge.

A.

Public Libraries

Public libraries offer their collections and services to all members of the community. The libraries may range in size from one-room facilities in sparsely populated rural areas to large multibranch systems that serve millions of people in urban areas. Urban public library systems generally maintain a large central library in the downtown area as well as several smaller branches—known as neighborhood or community libraries—in the various neighborhoods of the city. Some public libraries provide services to rural areas of their communities with bookmobiles, which are trucks, trailers, vans, or buses equipped to serve as traveling lending libraries.

A.1.

Access to Information

Public libraries strive to keep their collections and services open to all members of the community regardless of age, citizenship, occupation, economic status, educational level, ethnicity, or background. In the United States libraries express this principle of nondiscrimination in the Library Bill of Rights, a basic policy statement on access to libraries developed by the American Library Association (ALA). Supporters of public libraries tend to advocate the idea that citizens in a democratic society require free and equal access to information if they are to responsibly choose their elected leaders and vote on issues that affect their communities. For this reason, in the United States, Canada, and many other countries public libraries are generally considered guardians of the democratic principles of freedom, equality, and individual rights.

Not all users share the same reasons for using a library. For example, teenagers may go to the public library after school to study, to use computer workstations, or to socialize with friends. Families may use public libraries to gain access to recreational materials. Small-business owners may use public library collections to conduct research during the initial phases of forming a new business. Unemployed people use the collections to find information about job opportunities. Recent immigrants use the public library to gain language or literacy skills. With such diverse needs for information, public libraries face the increasingly difficult challenge of developing collections and services that reflect the full range of needs in their communities.

A.2.

Collections

Because they serve such a diverse range of people, public libraries maintain collections that can span the spectrum of human knowledge and opinions. Collections include printed materials such as reference sets, paperback novels, biographies, children’s and young adult literature, histories, newspapers, and magazines. They usually also contain photographs, maps, art reproductions, sound recordings, and video recordings. In addition to printed and audiovisual materials, most public libraries in the United States and Canada feature computer workstations with software, CD-ROMs, and connections to information worldwide through the Internet. As part of their mission to serve as a resource center for citizens in a participatory democracy, public libraries in the United States and Canada maintain collections of public records, public policy statements, government documents, and tax forms.

Large public library buildings are organized into different sections that focus on specific collections or services. For example, most large public libraries divide their collections into different departments arranged by subject. Each department is staffed by its own librarian or group of librarians. A library may maintain separate departments for business and technology, humanities, children’s materials, and government publications. Other typical features of large library buildings include reading rooms, special galleries for exhibitions, auditoriums for lectures or concerts, computer rooms, children’s rooms, photocopy rooms, and classrooms.

A.3.

Lending Materials

As part of their mission to provide information resources to the community, public libraries allow users to borrow items from their collections for limited amounts of time. To be eligible to borrow public library materials, a user must register her or his name, address, and other basic information with the local library’s circulation department, which keeps track of the library’s collections. Upon registering, users receive library cards, which they must present at the circulation desk when they wish to check out books or other materials. Some public libraries have self-checkout machines that automatically record the user’s name, the item borrowed, and the length of time the user may keep the item. Public libraries typically allow users to borrow most materials for two to four weeks, although the borrowing periods may be shorter for popular items such as video tapes and best-selling novels. For more information, see the Borrowing Library Materials section of this article.

A.4.

Services for the Community

In addition to maintaining diverse collections, public libraries offer an increasing variety of services and activities in response to community needs. Common services range from story hours, crafts, and puppet shows for children to computer technology workshops, concerts, and lecture series for users of all ages. Many public libraries sponsor exhibits about historical events and popular culture. In addition, they host book-discussion groups, lectures, film screenings, and live performances in auditoriums or public meeting rooms. Many public library staff members are specially trained to recommend books to users of particular age groups or with specific interests. The librarians who offer these services first discern the educational and recreational interests of a library user and then draw up a customized list of suggested titles for the user to read. For example, a librarian might prepare a list of items about the local court system for someone planning to testify in small-claims court. Or a children’s librarian might compile a list of picture books for use by child-care providers.

A.5.

Reference Services

Large public libraries employ professional reference librarians who assist users in finding information. Reference librarians are specially trained in research techniques that allow them to use the library’s resources most effectively. Some public libraries also maintain information hotlines staffed by reference librarians who provide brief answers to specific questions. Users can generally access these information hotlines via the telephone, e-mail, conventional mail, or fax. In addition, many libraries offer public information and referral services, which direct users to nonprofit community groups that address particular needs.

A.6.

Services for Children and Young Adults

Before the early 1900s, children under ten years of age were denied full borrowing privileges at public libraries. Today, public librarians consider service to youth a primary mission. Most public libraries feature children’s rooms, where children’s librarians and guest storytellers read stories to children to encourage a love of books and reading. Children’s rooms may also feature computer workstations equipped with software designed for children. Some libraries sponsor children’s programs in child-care centers, schools, homeless shelters, public housing facilities, and other locations. A few large public library systems in the United States and Canada feature special libraries for gifted children, for deaf or blind children, or for developmentally disabled children. As many as half the books circulated in some public libraries are borrowed by children.

Many public libraries also develop specialized collections and facilities to meet the unique needs and interests of teenagers and young adults. Young people in this age group have generally lost interest in children’s library materials, but many have not yet developed an interest in books and other materials from the collections designed for adult library users. Public librarians may be specially trained to interest teens and young adults in particular materials and to direct them to adult collections when they are ready. These librarians also attempt to reach young high school dropouts through contacts with community leaders, outreach centers, and employers. A major aim of library service to young people is to attract and keep them as readers of books and users of libraries in adult life.

A.7.

Multilingual Services

As part of an effort to expand their services to all potential users, public libraries in the United States and Canada normally include foreign-language materials in their collections. These materials serve multilingual populations in the community as well as recent immigrants. Because Canada has two official languages, French and English, Canadian public libraries maintain collections in both languages. Many Canadian public libraries also maintain collections in various native languages to serve indigenous populations of Canada. The National Library of Canada, located in Ottawa, supports such efforts with the Multilingual Biblioservice, which loans collections of materials in various languages to local libraries for extended periods. The National Library of Québec furthers such work by maintaining large collections of French-Canadian heritage.

A.8.

Administration

A public library is administered by a director who manages the staff and oversees all of the library’s daily operations. The director usually reports to a board of trustees made up of citizens interested in improving local library service. In some communities voters elect library board members, but usually trustees are appointed by the local mayor and approved by the city council. The board of trustees establishes the library’s operating policies, and the director is responsible for implementing those policies. In practice, however, it is customary for the director to identify the library’s needs and then to recommend policies to the board. After reviewing the director’s recommendations, the board can accept, modify, or reject the proposed policies. Although the director and the trustees often disagree about appropriate library policies, they must develop a strong working relationship based on mutual trust and respect if the library is to be successful in achieving its goals.

The number of trustees on a public library board varies from one library to the next, depending on rules established by the political jurisdiction the library serves. Ordinarily, a public library board consists of 6 to 12 trustees. Local laws almost always require trustees to live in the community they serve. Ideally, board members will reflect the various segments of their community. For example, trustees often come from a variety of cultural, economic, and professional backgrounds. Although most trustees have no professional experience as librarians, they are typically well educated and politically active. Trustees rarely receive financial compensation for their work.

The director of a public library is hired by the board of trustees. In virtually all public libraries in the United States and Canada, the director has professional training as a librarian. The director should also have strong organizational skills and leadership abilities. Aside from carrying out the policies established by the board, the director usually develops the library’s budget, which is then subject to approval by the board and the local government. The director and trustees also meet with political and business leaders, the media, and the general public to obtain input and feedback, to promote the library’s services, and to advocate for public funds. Because most public library revenue comes from local taxes, the financial security of public libraries depends on the director’s ability to secure popular support.

The public library director also manages the library’s personnel and directs staff members in the most critical library functions, such as selecting library materials and performing reference work. A large public library may divide its personnel into separate departments, each with a different function or specialty. A typical large public library may feature administrative departments such as reference services, to assist users with research; children’s and young adult services; audiovisual services, to manage materials such as videotapes and compact discs; circulation services, to facilitate the borrowing of materials; technical services, such as cataloging and classifying materials; and public relations services. Depending on the size of the library, each department is supervised by a department head, and individual librarians perform the specialized duties of their own particular department. In a small public library, where personnel and financial resources are limited, the library’s director and a few assistants may provide all of the library’s services without specializing in any particular area.

A.9.

Funding

In the United States and Canada, the idea of publicly funded libraries first gained widespread support in the 19th century. In nearly every community, local citizen groups and public officials petitioned municipalities to direct public funds for the establishment of libraries to serve the public free of charge. Public libraries quickly spread across the continent as advocates championed the library’s ability to function as the “people’s university,” where people of limited financial means could educate themselves at no cost to gain the knowledge and skills required to achieve upward mobility in society.

Over time, local governments have developed municipal libraries, which they directly fund with the budgets of villages, towns, cities, or counties. Today, nearly 80 percent of all public library revenue in the United States comes from local tax sources, especially from local property taxes. Some communities also fund their municipal libraries with other kinds of taxes, such as personal income taxes, sales taxes, and special taxes on specified products and services such as alcohol, tobacco, and entertainment. Although the bulk of public library budgets comes from local municipal budgets, the federal government also provides various grants to local public library districts for specific development projects.

Many communities face shortages in public funds for their libraries. As a result, public libraries often must restructure their budgets to spend more on access to information from online sources, such as the Internet, and less on acquiring materials for their own permanent collections. They also must often spend more on popular materials and less on important but esoteric or highly specialized resources.

In addition to relying on funds from public sources, public libraries actively solicit financial assistance from private individuals, organizations, and corporations. Most public libraries form special committees that seek financial gifts and grants from various private sources. In the United States and Canada, local residents organize volunteer groups, usually called Friends of the Library, that raise funds to supplement public library budgets. For example, Friends of the Library chapters raise funds for library materials such as special books and periodicals, for services such as literacy programs and reading groups, and for library amenities such as fountains and plants that make the library building more welcoming. The chapters raise these funds through activities such as selling annual memberships to individuals, sponsoring used-book sales, and selling tickets to lectures.

Many public libraries have responded to budget shortfalls by imposing user fees for some services. Public libraries have introduced fees for special services such as making photocopies of library materials, providing access to specialized online databases, and filling requests by businesses for reference services. Most studies estimate that between 70 and 80 percent of publicly supported libraries in the United States routinely charge various sorts of user fees. Critics of user fees at publicly supported libraries contend that such fees are a form of discrimination based on a user’s ability to pay. The American Library Association argues that librarians should develop “alternative models and methods of library administration that minimize distinctions among users based on their economic status or financial condition.”

A.10.

Major Public Libraries

The New York Public Library—consisting of 4 research libraries and 85 branch libraries—is the largest public library system in the United States. Founded in 1895, its collections total more than 13 million volumes. Other major public library systems in the United States include the County of Los Angeles Public Library, the Los Angeles Public Library, and the San Francisco Public Library, all in California; the Chicago Public Library, in Illinois; the Boston Public Library, in Massachusetts; the Brooklyn Public Library and the Queen’s Borough Public Library, both in New York; the Cleveland Public Library and the Cincinnati & Hamilton County Public Library, both in Ohio; the Free Library of Philadelphia and the Carnegie Library of Pittsburgh, both in Pennsylvania; and the Seattle Public Library, in Washington state.

The Toronto Public Library, founded in 1884 in Ontario, is the oldest and largest public library system in Canada. In 1998 it merged with the former library systems in several surrounding communities. The newly enlarged Toronto Public Library maintains collections of 9 million items in 98 branches. Other major public library systems in Canada include the Vancouver Public Library in British Columbia and the Ottawa Public Library in Ontario.

For information on public library systems in other countries, see the Libraries of the World section of this article.

B.

School Libraries

School libraries serve elementary schools, middle schools, junior high schools, and high schools. The main function of a school library is to support various educational programs and to develop students’ skills in locating and using information. Teachers use school libraries to access information needed to develop and support their classroom instruction. Students use the materials in school libraries to perform their class work.

School libraries usually maintain collections in a variety of media. In addition to books, magazines, and newspapers, school libraries may contain photographs, films, sound and video recordings, computers, CD-ROMs, games, and maps. Some school libraries contain realia, or real artifacts such as various types of stones for the study of geology. An increasing number of school libraries have computer labs with computer workstations, software, and Internet connections. Because school libraries often emphasize the variety of media in their collections, they are sometimes referred to as library media centers. Most school libraries further enhance their collections by becoming members of school library networks; this allows them to share resources with libraries in other schools.

School librarians—sometimes called media specialists—select library materials and offer instruction to promote access, delivery, and interpretation of information. For example, school librarians might ensure that their libraries’ collections contain information to assist students in completing particular classroom assignments. They might also offer classes in searching online catalogs for research materials. Once students locate materials, school librarians might help them interpret the information contained in these resources and apply it to their classroom assignments. School librarians typically have credentials in teaching as well as in library science. This allows them to participate in school administration and curriculum development in addition to managing their library duties.

Students at each educational level have unique needs and interests. Accordingly, libraries that serve different school levels maintain different types of collections and offer a different range of services.

B.1.

Elementary School Libraries

Elementary school libraries play a central role in early childhood education by offering young children some of their earliest encounters with books and other resources. These libraries generally feature illustrated children’s storybooks, coloring books, and audio and visual materials. Most elementary school libraries also contain reference materials such as encyclopedias, as well as fiction and nonfiction books aimed at older elementary school students. Some elementary school libraries feature computers with children’s educational software. In the primary grades (typically kindergarten through grade three) children attend special classes to help them develop basic skills in retrieving information from the library. Students learn how to search through their school library’s catalog, find a book on the shelves, and check out the book from the circulation desk. Elementary school students may also use the school library to browse through the materials, learn basic computer skills, or listen to stories.

A growing number of schools encourage students in the later grades of elementary school (typically grades four through six) to come to the library throughout the day to conduct research for school assignments, to read for pleasure, and to meet and work with their peers. This flexible scheduling allows schools to integrate research skills and library resources into daily classroom instruction.

B.2.

Middle School and Junior High School Libraries

Libraries at the middle school or junior high school level (typically grades six or seven through eight or nine) concentrate on maintaining students’ interest in gaining information and developing ideas. Classes at this school level usually introduce students to individual and small-group research projects. To adequately support classroom assignments, middle school and junior high school libraries usually offer larger and more varied collections than those at the elementary level. They also often supplement these collections with computer databases and more sophisticated bibliographic tools.

B.3.

High School Libraries

Libraries at the high school level (typically grades 9 or 10 through 12) differ in several ways from those serving the lower grades. Because classes at the high school level require students to conduct more research, high school libraries usually have larger and more advanced collections than do libraries in the lower grades. The collections of high school libraries are generally capable of supporting instruction in mathematics, science, technology, social sciences, the humanities, the arts, literature, and foreign languages. In addition, because students must spend more of their time conducting research, high school libraries are usually large enough to accommodate at least 20 percent of the entire student body at any given time. The best-equipped high school libraries feature computer labs, professional reference resources for teachers, conference and group study areas, and classrooms within the library. Most high school libraries also include separate areas devoted to college or vocational preparation. These areas typically contain information on individual colleges, examples of college applications, vocational aptitude tests, and other materials designed to provide guidance for graduating high school students.

B.4.

Funding

Schools in the United States have not always had a large number of libraries. As recently as 1958 about half of the public schools in the United States had no libraries at all. The number of public school libraries increased dramatically when the federal government passed the Elementary and Secondary Education Act of 1965, which provided funds for school districts to improve their education programs and facilities, including their libraries. Nevertheless, many educators claim that since the legislation was passed federal spending has not increased sufficiently to meet the rising cost of new library technologies such as computer databases and Internet access.

Because the federal government provides only limited funds to schools, individual school districts rely on funds from local property taxes to meet the vast majority of public school expenses. Therefore, the libraries of public schools tend to reflect the financial capabilities of the communities in which they are located. Districts in wealthy suburbs often have fully staffed libraries with abundant resources, spacious facilities, and curricular and instructional support. In contrast, school districts in many poor areas house their libraries in ordinary classrooms or in small rooms. The libraries in such areas are generally staffed by volunteers, who organize and maintain books that are often out-of-date, irrelevant, or damaged. See also Public Education in the United States.

C.

College and University Libraries

Research plays a central role in the academic work of students and faculty at colleges and universities. As a result, college and university libraries—also called academic libraries—are often considered the most important resource of an institution of higher education. Because students and faculty at colleges and universities may wish to conduct research within any conceivable academic discipline, the collections of academic libraries usually reflect a vast range of interests and formats. Academic libraries range in size from the modest collections found in small liberal arts colleges to the immense collections found at research universities. Research universities maintain some of the largest libraries in the world. Most academic libraries are linked to other libraries in cooperative networks, enabling them to share scarce and little-used materials required for advanced research. Many academic libraries open their collections to the public, although borrowing privileges are often limited for users not affiliated with the college or university.

Large research universities often have separate libraries within individual academic departments, schools, or colleges. For example, academic branch libraries may devote their collections exclusively to agriculture, art, chemistry, math, psychology, or other academic disciplines. Universities may also divide their libraries into undergraduate and graduate divisions. Undergraduate libraries typically offer relatively general materials needed to support study toward a four-year, undergraduate degree. Graduate libraries contain materials for more specialized study toward an advanced, graduate degree. Some academic libraries also have separate buildings for rare books, handwritten manuscripts, maps, and other specialized collections.

Academic libraries generally attempt to expand their holdings on an ongoing basis. However, during the 1990s acquisition of expensive printed materials began slowing at most academic libraries as more funds were devoted to the acquisition of new computers, telecommunications equipment for access to the Internet, and online databases.

Because of the complexity, range, and diversity of formats and information in academic libraries, colleges and universities offer programs to introduce incoming students and faculty to the institution’s library services. These programs are designed to teach new users effective ways to make use of a variety of reference tools and library search mechanisms. In some parts of the United States, college accreditation agencies require institutions to offer library-sponsored courses on information retrieval and evaluation. See also Colleges and Universities.

D.

Research Libraries

Research libraries contain collections of unique materials to support the needs of advanced and highly specialized scholarship. These collections may include rare manuscripts and books, scientific documents, important printings of literary works, regional histories, genealogies, original musical scores, or other distinctive scholarly resources. Because these collections may contain many rare and valuable materials, their use is typically confined to the library buildings. Research libraries often publish scholarly studies of the materials in their collections, sponsor lectures and colloquia, and arrange exhibitions of their most important holdings.

Most colleges and universities have rare books or special collections departments in their libraries, and many maintain research libraries devoted entirely to such collections. For example, the Beinecke Rare Book and Manuscript Library at Yale University in New Haven, Connecticut, maintains early manuscripts and rare books in the fields of literature, theology, history, and the natural sciences. Also notable is the Thomas Fisher Rare Book Library at the University of Toronto. This library maintains diverse collections ranging from a 1789 bc Babylonian cuneiform tablet to British and French literature and to works by contemporary Canadian writers.

Many important research libraries are unaffiliated with a college or university. For example, the Folger Shakespeare Library in Washington, D.C., is an independent library that maintains the world’s largest collection of printed works by English poet and playwright William Shakespeare, in addition to books and manuscripts from the Renaissance on a variety of subjects. The Newberry Library in Chicago houses notable collections in history, literature, and the fine arts. The Library Company of Philadelphia, in Pennsylvania, specializes in American history from the 17th through the 19th century. The library of the American Philosophical Society, also in Philadelphia, is a center for research in the histories of science, medicine, and technology. The American Antiquarian Society in Worcester, Massachusetts, maintains collections in early American history. The Huntington Library, Art Collections, and Botanical Gardens in San Marino, California, has an extensive collection of rare books and manuscripts of British and American history and literature. The Family History Library in Salt Lake City, Utah, has the world’s largest collection of genealogical materials. It is operated by the Church of Jesus Christ of Latter-day Saints. The Pierpont Morgan Library in New York City contains large collections of early printed books, medieval manuscripts, early book bindings, and American historical documents.

Although some research libraries permit only selected scholars to access their collections, many notable research libraries in the United States open their collections to the general public. The four research centers of the New York Public Library contain more than 40 million items, making it the world’s largest publicly accessible research library complex. Its research centers consist of the Center for the Humanities, housed in the Central Research Building of the library; the New York Public Library for the Performing Arts, located in the Lincoln Center complex; the Schomburg Center for Research in Black Culture, in Harlem; and the Science, Industry and Business Library, located in the Manhattan business district on Madison Avenue. The rare books and manuscripts division, housed in the Center for the Humanities, maintains a strong collection of Americana, especially books printed before 1801. Notable rarities include the only known copy of the 1493 Barcelona, Spain printing of the letter by Italian Spanish explorer Christopher Columbus announcing his arrival in the New World; the Bay Psalm Book, printed in 1640, which was the first book printed in what would become the United States; and a copy of the first printing of the Declaration of Independence in 1776. The division also has a complete copy of a Gutenberg Bible, printed sometime between 1450 and 1456, as well as impressive collections in the fields of English and American literature, children’s literature, and science fiction. The library’s manuscript holdings include British and American historical documents and excellent examples of medieval illuminated manuscripts.

The Boston Public Library, founded in 1848, also houses a vast research collection that is open to the public. The library’s holdings include more than one million rare books and manuscripts; maps; original musical scores by Austrian composer Wolfgang Amadeus Mozart, Russian composer Sergey Sergeyevich Prokofiev, and others; several first-edition folios by William Shakespeare; and the personal library of John Adams, the second president of the United States.

Many research libraries are members of organizations that allow them to jointly publish catalogs of their holdings, collectively purchase library materials, and share other resources. The Association of Research Libraries represents more than 120 libraries in Canada and the United States. The organization serves as a forum to address common concerns of research libraries, to forge coalitions among libraries, and to support innovation and improvement in library operations. The Center for Research Libraries in Chicago enables more than 160 member libraries in Canada and the United States to collectively store, preserve, and distribute infrequently used materials.

Most large research libraries in the United States publish descriptions and locations of their collections in catalogs compiled by online bibliographic programs such as the Online Computer Library Center or the Research Libraries Information Network. Smaller research libraries in the United States list their holdings in the National Union Catalog of Manuscript Collections, a compendium of research library collections published by the Library of Congress. Scholars use all of these catalogs to locate materials in research libraries throughout the country.

E.

Special Libraries

Many corporations, private businesses, government agencies, museums, religious institutions, hospitals, associations, and other organizations maintain their own libraries to serve the specialized needs of their employees or members. These libraries are commonly called special libraries, but they may also be called information centers, research centers, or technical libraries. The collections of special libraries depend on the specific needs of the organizations they serve. For example, a law firm may maintain its own library of legal documents for use by its lawyers and staff, while a hospital may operate a library of materials in the health sciences to serve its doctors and nurses. In addition to performing the same functions as other libraries, special libraries evaluate, package, and present information to users in ways designed to increase productivity and add to the efficiency of their parent organization. They achieve these goals by reducing the time that employees spend searching for data and by providing information that facilitates improved decision making.

Special librarians must be able to design and manage library collections and services to meet the specific needs of the individuals or organization being served. To do this, they require in-depth knowledge of the sources of information in specialized subject areas such as biology, business, and law. They often hold degrees in these subject areas in addition to master’s degrees in library or information science.

The Special Libraries Association represents special librarians from the United States, Canada, and other countries. The organization is divided into units of various fields of specialization, such as aerospace engineering, chemistry, law, and petroleum and energy resources. The Special Libraries Association facilitates interaction among special librarians in a given field, promotes continuing education among special librarians, and helps special librarians build problem-solving networks.

F.

Government Libraries

Most governments of the world maintain libraries to serve the needs of elected officials and their staff members. Usually these libraries are open to the general public as well. The United States maintains government libraries at both the national and the state level. Canada has government libraries at the national, provincial, and territorial levels. In addition, most governments maintain national archives, which collect and maintain historical records, including government documents of enduring value.

A national library acquires, preserves, and promotes its country’s published heritage by acquiring copies of as many domestically created works as possible. In the United States, Canada, and most other countries, authors are required to submit copies of their published work to the national library in order to receive copyright protection for that work. By functioning as legal copyright depositories, national libraries collect and preserve their country’s cultural heritage. Most national libraries also create national bibliographies, which list information about every publication in their country.

Some of the largest and most prestigious national libraries in the world are the Library of Congress in Washington, D.C.; the Bibliothèque Nationale de France in Paris; the British Library in the outskirts of London; and the Russian State Library in Moscow. The following sections describe national libraries in the United States and Canada. For information on national libraries in other parts of the world, see the Libraries of the World section of this article.

F.1.

National Libraries in the United States

The United States government maintains four national libraries, all based in or near Washington, D.C. These are the Library of Congress, the National Agricultural Library, the National Library of Medicine, and the National Library of Education.

The Library of Congress, established in 1800, is the largest and most comprehensive library in the world. It functions as the country’s national library and as the research arm of the Congress of the United States. With more than 130 million items (including more than 17 million books) and with services unmatched in scope by any other national library, the Library of Congress is one of the world’s leading cultural institutions. Its primary function is to serve the U.S. Congress and its staff, but it provides extensive services to the general public as well. The Library of Congress also serves as the official copyright agency of the United States. In addition, the library collects materials from throughout the world in more than 450 languages, maintains one of the world’s most comprehensive law libraries, and houses the world’s largest collection of maps, atlases, printed and recorded music, motion pictures, and television programs. It also serves as the national library for the blind and physically handicapped, sponsors exhibitions on a variety of topics, and is a research center for the preservation and conservation of library materials.

The National Agricultural Library is one of the world’s largest agricultural research centers. Founded in 1862 as the departmental library for the United States Department of Agriculture, it was declared a national library by the U.S. Congress in 1962. The National Agricultural Library now serves to increase the availability and utilization of agricultural information for researchers, educators, policymakers, consumers of agricultural products, and the public.

The National Library of Medicine is a division of the National Institutes of Health. It collects materials in all fields of the health sciences. With more than 5 million items in its collection, the National Library of Medicine is the world’s largest research library devoted to a single scientific or professional field. The library serves physicians, nurses, hospitals, government agencies, commercial and nonprofit organizations, students, medical schools, and other libraries. The library also publishes Index Medicus, a listing of articles from thousands of medical journals around the world. In addition, the National Library of Medicine maintains MEDLARS (Medical Literature Analysis and Retrieval System), a vast system of computer databases that allows users around the world to search lists of publications and to retrieve factual information on specific medical questions. See National Institutes of Health: National Library of Medicine.

The National Library of Education was established in 1994 as part of a school reform law entitled Goals 2000: Educate America Act. The National Library of Education is the central division of a national network of libraries, archives, and other providers of information in the field of education. Its primary function is to serve the staff of the U.S. Department of Education, but it also serves other federal employees, the Executive Office of the President, the United States Congress, schools, educational centers, the general public, and other libraries.

F.2.

State Libraries in the United States

Most states also maintain libraries. As agencies of the state governments, the principal function of these libraries is to provide reference and loan services to governmental officials and staff. Most also offer limited services to the general public. In addition, they administer state and federal aid programs for all kinds of libraries, provide leadership and consultation for other libraries, and coordinate interlibrary lending networks for libraries within their given state. Most state libraries maintain archives divisions that collect and preserve official records and documents of state or provincial history.

F.3.

Other Government Libraries in the United States

Many other departments and agencies of the U.S. federal government maintain their own libraries. Some of the largest of these are administered by the Department of Defense for the various branches of the armed services. Each branch of the United States military also maintains libraries on its bases around the world to provide U.S. military personnel with technical information and leisure reading materials. The Department of State operates libraries (also called information resource centers) in many foreign countries as part of an effort to promote U.S. interests abroad. Other important federal libraries are maintained by the Department of the Interior, the Department of Justice, the Department of Commerce, the National Weather Service, the Office of Management and Budget, the Patent and Trademark Office, and the Environmental Protection Agency. The Smithsonian Institution also operates a variety of libraries in its various branches, which collectively maintain more than 1.2 million volumes covering subjects such as African art, Native American history, and space exploration.

F.4.

National Libraries in Canada

Canada’s national government maintains three main libraries in the national capital, Ottawa, Ontario. These are the National Library of Canada, the Library of Parliament, and the Canada Institute for Scientific and Technical Information. In addition, the Bibliothèque Nationale du Québec acts as the legal copyright depository for publications in the province of Québec.

The National Library of Canada, established in 1953, provides facilities for scholarly research to the government and the public. The library’s collection numbers more than 16 million items covering a wide range of subjects. Most of the library’s collection deals with issues relating specifically to Canada, making it the world’s foremost center for research in Canadian studies. The library publishes the Canadian Union Catalog, a listing of its collections and of the holdings of other major Canadian academic, public, and special libraries. The National Library of Canada also coordinates networks with other libraries in the country through which they share collections, technology, resources, and staff expertise. In addition, the library publishes Canadiana, a monthly and annual bibliography of new publications about Canada.

The Library of Parliament, established in 1867, provides information, reference, and research services to the country’s lawmakers and their staff members, parliamentary committees, and various legislative associations and delegations. It also offers information about the Canadian Parliament to the general public. The library’s public information resources include reports on current events, legislative summaries, newspaper-clipping services, reading lists, and online databases.

The Canada Institute for Scientific and Technical Information is a major research center for information in all areas of science, technology, engineering, and medicine. Established in 1916 as the library of the National Research Council of Canada, the institute now serves the Canadian government as well as the industrial, medical, and academic communities of Canada. In addition to its main catalog, the Canada Institute for Scientific and Technical Information provides access to the catalog of the Canadian Agricultural Library. This catalog features books, reports, and conference proceedings on agricultural information around the world. The institute also publishes international research journals in printed and electronic formats.

F.5.

National Archives

The National Archives and Records Administration is an independent agency of the United States government that selects, organizes, and preserves various public documents that it determines to be of enduring historical value. It also strives to make these materials easily accessible to the government and the public. The National Archives and Records Administration is located in Washington, D.C., and in College Park, Maryland. It preserves various treaties, laws, maps, charts, census data, presidential proclamations, executive orders, photographs, sound recordings, motion pictures, correspondence of government officials, computer data, and many other types of records. All of this amounts to a staggering amount of data, and the collection is steadily growing. In 1999 the National Archives held 4 billion pieces of paper; nearly 14 million still photographs and posters; more than 300,000 reels of motion-picture film; more than 5 million maps, charts, and architectural drawings; and more than 9 million aerial photographs. Among these documents are national treasures such as the Declaration of Independence, the Constitution of the United States, and the Bill of Rights. Fewer than 3 percent of the government’s records have enough lasting historical or legal significance to become a permanent part of the National Archives.

The National Archives and Records Administration also oversees several presidential libraries located throughout the country. Presidential libraries preserve and make available the papers, records, and other historical materials of individual United States presidents and their administrations. Most U.S. presidents since Herbert Hoover (president from 1929 to 1933) have been honored with their own presidential library, usually located in their home state. For example, the John F. Kennedy Library, located in Boston, Massachusetts, maintains more than 34 million manuscript pages (including 8.4 million pages of Kennedy’s own papers), as well as photographs, printed materials, films and videos, audio tapes, and many other materials dedicated to preserving the memory of Kennedy. Most presidential libraries also sponsor educational programs, special exhibitions, lecture series, and other events designed to serve the public. Other presidential libraries in the United States include the Rutherford B. Hayes Presidential Center in Fremont, Ohio; the Herbert Hoover Presidential Library and Museum in West Branch, Iowa; the Franklin D. Roosevelt Library and Museum in Hyde Park, New York; the Harry S. Truman Library and Museum in Independence, Missouri; the Eisenhower Center in Abilene, Kansas; the Lyndon Baines Johnson Library and Museum in Austin, Texas; the Richard Nixon Library in Yorba Linda, California; the Gerald R. Ford Library in Ann Arbor, Michigan; the Jimmy Carter Library in Atlanta, Georgia; the Ronald Reagan Presidential Library and Museum in Simi Valley, California; the George H. W. Bush Presidential Library and Museum in College Station, Texas; and the William J. Clinton Presidential Library and Museum in Little Rock, Arkansas.

The National Archives of Canada in Ottawa, Ontario, selects, preserves, and makes available public and private records of historical significance to Canada and its citizens. The archives include government records, maps, photographs, private papers, architectural drawings, paintings, audio and visual materials, and computer data. The census records in the archives make the institution a primary resource for Canadians conducting genealogical research. In addition, the National Archives of Canada supports other research activities and sponsors exhibitions on Canadian history.

III.

How Libraries Acquire Materials

Libraries must constantly revise and update their collections to ensure that the information they offer is reliable, up-to-date, and valued by their users. Because different types of libraries strive to satisfy different user needs, each library develops its own criteria for evaluating the quality of its collections. Using these evaluations, librarians can determine which areas of the collection most require additional resources.

National libraries generally try to ensure that they have at least one copy of every domestically published work as well as a representative selection of foreign works. University and school libraries measure the quality of their existing collections by assessing their ability to support teaching and research at their institutions. These libraries also typically measure the size of their collections or check lists of recommended materials to determine whether the library owns such documents. Public libraries usually judge the quality of their existing collections by determining how often users borrow certain materials.

Once librarians assess the quality of their existing collections, they must select and acquire new library materials. Most libraries can buy only a small fraction of the millions of books, periodicals, CD-ROMs, audio and video recordings, and other materials published every year. Large libraries may hire librarians who specialize in the selection of library materials, a process known as collection development. In smaller libraries, senior librarians and other staff members may share responsibilities for developing the library’s collection.

Unlike national libraries, which typically select all domestic works for their collections, university and school libraries generally select only those works judged by librarians and faculty members to have genuine literary or scholarly merit. Because public librarians must select materials to satisfy the demands of the general reading public, they base their selections almost entirely on readership, circulation, and anticipated demand rather than on the perceived quality of the work. The librarians who select materials for any type of library must balance the needs of their particular clientele with budgetary constraints, space limitations, and other considerations.

No one library can own everything needed to satisfy its clientele. Therefore, libraries increasingly emphasize access to materials rather than ownership of materials. For example, libraries may arrange to provide users with access to materials held by other libraries. This cooperation between institutions allows libraries to collectively offer much more comprehensive collections than any one library could offer by itself. Libraries also increasingly provide access to electronic versions of materials instead of stocking the physical materials on the library shelves.

Libraries acquire their materials from a variety of sources. The United States Government Printing Office provides libraries in the United States with materials published by the U.S. Congress and by various government departments and agencies. Many libraries—particularly special libraries with rare-book and historical collections—acquire a significant number of their materials as gifts from various organizations, foundations, and individuals. Large libraries often administer approval plans, in which booksellers select materials and send them to libraries in subject areas of interest. The libraries pay for the materials they want to add to their collections and return whatever they do not need. When libraries purchase their materials, they often negotiate discounts from publishers, book dealers, and others in order to stretch the library’s budget as far as possible.

At some point, all types of libraries must remove older, irrelevant, or infrequently used materials to make space for new acquisitions. This process is sometimes referred to as weeding the collection. Libraries with sufficient budgets may store the removed materials in warehouses or other facilities where they can be accessed on demand. Frequently, however, libraries donate their removed collections to other institutions or sell them in public book sales. In some cases, libraries must destroy these materials.

IV.

Organization of Resources

Because libraries usually contain a vast amount of material, users might never find the information they need if this material were not carefully organized. For this reason librarians have developed systematic procedures to organize their collections in ways that provide users with convenient and logical access to materials.

Although no two libraries are organized in exactly the same way, nearly all libraries use some type of system to catalog, or index, their collections. In addition, libraries use similar systems to classify and arrange their materials on library shelves. For these reasons, library users require a basic understanding of the common types of catalogs and the principles of classification to easily find the information they need.

A.

Catalogs

A library catalog is an index to the library’s collection that enables a user to find materials. Library users can determine whether the library owns the materials they need by searching through catalog records. In many cases the information provided on the record will enable the patron to make a decision about whether the item listed suits his or her needs. Catalog records typically list the item’s author, its title, its subjects, the date it was published, the name of its publisher, and other information. In addition, the catalog record contains the item’s call number, a combination of letters and numbers used to classify the work. The call number also indicates the item’s location in the library. For example, a book on architecture is classified—and arranged in the library—with the library’s other books on architecture.

Library catalogs may limit their listings to the items the library owns, or they may include listings for the holdings of other libraries as well. Library catalogs that list the holdings of multiple libraries are called union catalogs. Libraries list their holdings in several different kinds of catalogs, including book catalogs, card catalogs, microform catalogs, and computerized catalogs in either CD-ROM or online format. The majority of library patrons now use computerized catalogs.

A.1.

Book Catalogs

Book catalogs list the holdings of the library in a catalog in book form. Libraries first introduced book catalogs in the late 16th century, and they remained popular for some 300 years. The book catalog features complete information about each item, usually under the name of the author. Alternate listings organized by title or subject usually contain brief descriptions of each item. Librarians consider the portability of the book catalog to be a major advantage. Book catalogs are also relatively inexpensive to produce in multiple copies. The book catalog’s great disadvantage is that it is not easily updated; libraries must issue supplements to list new items that the library has acquired. Few modern libraries continue to publish book catalogs.

A.2.

Card Catalogs

Card catalog entries are printed on cards that libraries arrange alphabetically in drawers. A card catalog usually contains three types of cards for each item in the library’s collection. The first type has the author’s name or other persons or institutions that contributed to the work on the top line, the second has the title of the book or other item on the top line, and the third has the subject of the item on the top line. Usually the subject heading is printed in all capital letters or in red for further emphasis. Each drawer in the library’s card catalog has a label telling what letters are included in it.

The card catalog largely replaced the book catalog in the late 19th century because it could easily be expanded by filing new cards as the library added new materials. In addition, more than one person could use the card catalog at any given time. The card catalog’s acceptance was enhanced in 1901, when the Library of Congress began to sell copies of its catalog cards to other libraries. The card catalog system is still widely used, although its popularity began to decline when libraries adopted computerized catalogs.

A.3.

Microfiche Catalogs

A microfiche catalog is similar in organization to a book or card catalog, but its format is different. Microfiche is a small sheet of film printed with rows of very small images that can be viewed using a library’s microfiche viewer, which magnifies the images. A microfiche catalog allows libraries to store vast amounts of catalog information in much smaller spaces than printed catalogs require. Whereas book catalogs and a few card catalogs list complete entries only under the author’s name, all entries in a microfiche catalog are usually complete. This means that each entry will contain the item’s author, its title, its subjects, its call number, the date it was published, the name of its publisher, and other information. Despite this advantage, only a few library users can access the typical library’s limited number of microfiche viewers at any given time. Although many libraries maintain microfiche catalogs, most rely primarily on their computerized catalogs.

A.4.

Computerized Catalogs

Often referred to as online public access catalogs (OPACs) or online catalogs, computerized catalogs were first introduced in libraries in the early 1980s. Online catalogs provide broader access to a library’s collection by allowing more sophisticated searching of the catalog. They are also updated easily. They can be searched from locations outside the library building through the Internet. In addition, many libraries have integrated their online catalogs with their circulation systems, providing information on the status of a book’s availability in the library in addition to the usual cataloging information. This useful feature has never been a characteristic of other catalog formats. Despite these advantages, libraries with small operating budgets have difficulty raising the funds to convert book catalogs, microfiche catalogs, or card catalogs into machine-readable formats that computers can use.

A.5.

Catalog Descriptions of Library Materials

Librarians give careful consideration to the ways in which they describe their documents so that users can easily search library catalogs to determine whether the library has specific items. Rules for describing all forms of library materials are governed by cataloging codes developed at the national or international level. Cataloging codes set standards for the types of information that a catalog should include and for the format in which that information should be presented. By establishing consistency in the content and format of catalog descriptions, these standards simplify the user’s search for library materials. In addition, standardized catalog descriptions enable libraries to easily share information about their collections with one another.

In the United States, libraries first attempted to establish a standard for catalog descriptions in the late 19th century. Since then, libraries in the United States, the United Kingdom, Canada, and a number of other countries have adopted a standard set of rules for describing documents in their collections. These rules, called the Anglo-American Cataloguing Rules (AACR), were first published in 1967 and were issued in a second edition in 1978 (AACR2). The AACR2 outlines common principles of catalog description that apply across all document formats. It also gives specific rules needed to describe particular types of documents. For example, information needed to describe videotapes will vary somewhat from that needed to describe books, sound recordings, or computer files. In the early 1970s the International Federation of Library Associations and Institutions (IFLA) developed different international standards for describing all types of library documents. These standards, called the International Standard Bibliographic Description (ISBD), form the basis for many of the national cataloging codes that were subsequently developed around the world.

Although cataloging codes were once primarily designed to serve users of large research libraries, more recent standards allow for different levels of detail to meet the needs of users in other types of libraries. These variations recognize that a user in a large research library may need or want to know far more about a document than a patron in a public library or a student in a school library. For example, a card-catalog record developed for a research library might look like this:

• Queenan, Joe.
• If you’re talking to me, your career must be in trouble : movies, mayhem, and malice / by Joe Queenan.—1st ed.—New York : Hyperion, ©1994.
• xix, 267 p. ; 24 cm.
• Essays first published in Movieline, Rolling Stone, and the Washington Post.
• Includes index.
• ISBN 1-56282-788-X
• 1. Motion pictures—United States—Reviews. 2. Motion pictures—United States—Humor. I. Title.

Public or school libraries might choose to eliminate some of this information from their catalog descriptions. For example, they may omit the subtitle (“movies, mayhem, and malice”), the place of publication (New York), the size (24 cm), the note about where the essays were first published, and the note that there is an index. For special situations, elements might be added to the description if the librarians believe this would be useful. For example, if the library’s copy of the book is autographed by the author, the cataloger might wish to note that fact.

The form of information on the typical catalog card remained relatively stable from the late 19th century until the advent of online catalogs in the 1980s. Online catalogs have changed the presentation of catalog information considerably. Although some online catalogs have elected to present entries in a screen display that resembles the catalog card, most have chosen to use a master catalog record that contains complete catalog information about a given item. From this master catalog record, users can generate computer displays of varying amounts of information, depending on their needs. For example, the user may establish parameters in a search that would generate the following level of display, which provides only basic information to identify the document:

• AUTHOR: Queenan, Joe.
• TITLE: If you’re talking to me, your career must be in trouble : movies, mayhem, and malice.
• PUBLISHER: Hyperion, ©1994.
• SUBJECTS: Motion pictures—United States—Reviews. Motion pictures—United States—Humor.
• LIBRARY HOLDINGS:
• LOCATION: Main Library CALL NUMBER: PN1995.Q44 1994
• STATUS: Checked out

The user can also use the computer catalog to generate a more complete or full display that provides additional information. A full display for the previous record could be as follows:

• AUTHOR: Queenan, Joe.
• TITLE: If you’re talking to me, your career must be in trouble : movies, mayhem, and malice / Joe Queenan.
• PUBLICATION: New York, N.Y. : Hyperion, ©1994.
• DESCRIPTION: xix, 267 p. ; 24 cm.
• NOTES: Essays first published in Movieline, Rolling Stone, and the Washington Post.
• NOTES: Includes index.
• SUBJECT: Motion pictures—United States—Reviews.
• SUBJECT: Motion pictures—United States—Humor.
• LIBRARY HOLDINGS:
• LOCATION: Main Library –CALL NUMBER: PN1995.Q44 1994
• STATUS: Checked out

Some names associated with library materials present peculiarities that complicate searches in library catalogs. For example, some authors publish works under more than one name. American author Mark Twain wrote under this celebrated pseudonym, but he also wrote under his given name, Samuel Langhorne Clemens. Cataloging standards call for the use of the name that appears in the work being cataloged. Logically, users may search under Twain for books written under the name Twain, but they must search under Clemens to find those books written under the author’s given name. To assist catalog users who search only under the secondary name, or under a name used for only some of a person’s works, catalogers typically provide cross references in the catalog. In card and book catalogs, these cross references direct users to “see” or “see also” an alternate name. A library that cataloged a work under Mark Twain but did not own any books that had Samuel Langhorne Clemens as author would likely provide the following reference:

• Clemens, Samuel Langhorne see Twain, Mark.

If the library had books for which Clemens was listed as the author and others for which Twain was the author, the references would likely read as follows:

• Clemens, Samuel Langhorne see also Twain, Mark.
• and
• Twain, Mark see also Clemens, Samuel Langhorne.

In these situations, users could search under either name and they would find either the catalog record or a reference instructing them on how to find the alternate name in the catalog. In some online catalogs, these instructions may not actually appear on the screen. Instead, electronic links may be made for the user so that a search on either “Twain” or “Clemens” would display catalog records for all books written under either name.

B.

Classification Systems

Library classification systems enable libraries to bring together in one place all works dealing with the same subject. Placing similar materials in one location helps users find multiple items on a given subject more efficiently than they could if those same items were scattered around the library. Classification also facilitates browsing for related materials, since all related materials share similar classifications. In libraries in the United States, the two most frequently used classification systems are the Dewey Decimal Classification (DDC), which is used primarily in public and school libraries, and the Library of Congress Classification, which is used most often by academic and special libraries.

B.1.

Dewey Decimal Classification

In the mid-19th century, most libraries used locally developed classification systems to arrange their collections. These systems usually provided a broad indication of the subject and gave a permanent location for a book on a shelf. This situation changed dramatically with the introduction of the Dewey Decimal Classification. American librarian and library educator Melvil Dewey devised the system in 1873 while he was a student at Amherst College in Massachusetts. The Dewey Decimal system was first published in 1876 as A Classification and Subject Index for Cataloguing and Arranging the Books and Pamphlets of a Library.

In structuring his system, Dewey used numbers and decimal fractions to indicate the subject content of a given work. For example, the numbers 200-290 denote all works on the subject of religion, and the numbers 900-990 denote all works on the subject of geography and history. This approach to notation allowed for a representation of a variety of subject categories, or classes, and subclasses. It also expressed the hierarchical relationship of these classes and subclasses while allowing unlimited expansion for additional subclasses. These new subclasses are introduced in new editions of the Dewey Decimal system, published every six to ten years. Although the names of the principal classes have changed over time, their content has remained stable. Today, the ten primary classes are as follows:

• 000 Generalities
• 100 Philosophy and psychology
• 200 Religion
• 300 Social sciences
• 400 Language
• 500 Natural sciences and mathematics
• 600 Technology (applied sciences)
• 700 The arts; fine and decorative arts
• 800 Literature and rhetoric
• 900 Geography and history

The Dewey Decimal Classification is based on multiples of ten (the word decimal in the name of the classification system comes from decem, the Latin word for “ten”). Thus, each of the ten main classes has the potential to be broken down into smaller multiples of ten. For example, class 500 (natural sciences and mathematics) has the following subclasses:

• 500 Natural sciences
• 510 Mathematics
• 520 Astronomy and allied sciences
• 530 Physics
• 540 Chemistry and allied sciences
• 550 Earth sciences
• 560 Paleontology; paleozoology
• 570 Life sciences; biology
• 580 Plants
• 590 Animals

Each of these classes may then be further divided. For example, the subclasses of 540 are as follows:

• 540 Chemistry and applied sciences
• 541 Physical and theoretical chemistry
• 542 Techniques, equipment, and materials
• 543 Analytical chemistry
• 544 Qualitative analysis
• 545 Quantitative analysis
• 546 Inorganic chemistry
• 547 Organic chemistry
• 548 Crystallography
• 549 Mineralogy

Each of these classes may be divided ten additional times and those ten more times, and so forth. At each step of the hierarchy, one additional number from 1 to 9 is added to the length of the notation. Thus, class 500 (natural sciences and mathematics) has subclass 540 (chemistry and applied sciences); a subclass of 540 is 541 (physical and theoretical chemistry), a subclass of 541 is 541.3 (physical chemistry), and so on.

Because this notation generally reflects the position of the class within the hierarchical structure of concepts, the Dewey Decimal Classification system provides libraries with a great deal of flexibility in tailoring their classification to their collections and the needs of their users. For example, a library with a considerable collection of works dealing with cats might classify them very specifically. A book on Siamese cats could be placed in the class 636.82 (short-haired cats) or in an even more detailed class, 636.825 (Asian short-haired cats), while a book on Maine coon cats would be placed in 636.83 (long-haired domestic cats). This detailed indication of subject is called close classification. A library with more limited holdings on cats might elect to place all of those works in the general class number for cats, 636.8, regardless of the specific nature of individual books or documents. This classification strategy is known as broad classification.

This ability to customize the detail of classification is one of the strengths of the Dewey Decimal system, because it provides for unique library and user needs. However, this ability is also one of the major shortcomings of the system, because each library’s tailoring of the class number results in a certain amount of inconsistency when libraries share information about their collections with each other. Ideally, when one library has classified a work, other libraries should be able to use that same classification number. However, one library may have classified the document broadly while another may have preferred close classification.

The Dewey Decimal Classification number that appears on the spine label for a book is part of the call number. In a library using Dewey Decimal Classification, the call number is a combination of the Dewey Decimal number and an alphanumeric (consisting of both letters and numbers) notation that usually represents the surname of the author and the initial letter of the first word of the title. This secondary notation is called the book number or the cutter number. It was developed and popularized in the late 19th century by Charles A. Cutter, a librarian in Boston. For example, the call number for the book The World of Antiques, by Richard Landon, might be

• 745.1
• L259w

The Dewey Decimal number is 745.1 and the cutter number is L259w. The alphanumeric combination L259 in the cutter number is derived from a special table to represent the name Landon, while the w represents the first significant word of the title, world. If Landon wrote other books on antiques, the use of a letter to represent the title would allow librarians to easily arrange his books alphabetically on the shelf. In a smaller collection, the cutter number is often simplified by indicating the first few letters of the author’s name. For the same book, a simplified call number might be

• 745.1
• Lan

In the first half of the 20th century, the Dewey Decimal Classification was the most widely used classification system in American libraries. Beginning in the 1960s a major movement began, principally among academic libraries, to change their collections from the Dewey Decimal system to the Library of Congress Classification system. There were two primary factors behind this movement: (1) the shortcomings of Dewey Decimal Classification for sharing materials between libraries, and (2) the limitations of Dewey Decimal Classification in handling new subjects without introducing major changes in the system. The cause of this latter problem is that the Dewey system had identified most major classes and subclasses when it was first created, leaving few vacant places for new subjects as they developed over the years. New subjects must be placed within the existing structure, resulting in increasingly longer classification numbers, or worse, in the need to completely revise major parts of the classification of a library’s collection. Beginning in the 1960s, new developments in scholarship and technology necessitated major revisions of the Dewey Decimal Classification’s system for the subjects of psychology (150), sociology (301), law (340), public administration (350), education (370), mathematics (510), and the life sciences (560-590). In addition, each new edition of the Dewey Decimal Classification has introduced hundreds of other minor classification and notation changes.

Despite its shortcomings, the Dewey Decimal Classification system remains a cornerstone for the organization of library materials. In addition to its widespread use in the United States and Canada, it has been translated into a number of languages, including French, Spanish, German, Arabic, and Russian, making it the most widely used library classification system the world. The system is continuously revised to keep pace with knowledge in all areas. The Dewey Decimal Classification system is published by Forest Press, which in 1988 became a division of OCLC: Online Computer Library Center, an international computer-based library utility with headquarters in the United States. This acquisition sparked increased OCLC research into the use of the Dewey system for the retrieval of information from the Internet.

B.2.

Library of Congress Classification

In contrast to the Dewey Decimal Classification, which was developed by a single person, the Library of Congress (LC) Classification evolved as a collaborative effort. In 1898 a group under the guidance of J. C. M. Hanson, the head of the catalog division at the Library of Congress, and Charles Martel, the library’s chief classifier, developed the first part of the classification system. Their work established the subject areas for bibliography work and for library science. In the years that followed, numerous specialists contributed to the further development of the Library of Congress system and expanded it to cover other subject areas.

The Library of Congress Classification system is divided into 21 major classes, using letters for each. The system does not use the letters I, O, W, X, and Y. The major classes of the Library of Congress Classification system are as follows:

• A General works
• B Philosophy; psychology; religion
• C Auxiliary sciences of history
• D History: General and Old World
• E-F History: America
• G Geography; anthropology; recreation
• H Social sciences
• J Political science
• K Law
• L Education
• M Music and books on music
• N Fine arts
• P Languages and literature
• Q Science
• R Medicine
• S Agriculture
• T Technology
• U Military science
• V Naval science
• Z Library science

Originally, the Library of Congress Classification system designated the main class of a subject by using a single letter in the call number. However, as the classification introduced new subjects, it used a second letter to further subdivide the main classes into subclasses. For example, H indicates the broad subject of social sciences, and HF denotes the more specific subject of commerce. Class K (law) is the only part of the classification to use a third letter to further subdivide the second-level classes. For example, class KL represents the history of law in various regions of Eurasia, and KLA represents materials specific to Russia and the former Union of Soviet Socialist Republics (USSR). In all classes, the letter or letters are followed by a number of up to four digits, further dividing subjects and making the Library of Congress Classification an alphanumeric notation. These numbers themselves may be further expanded with decimal figures to represent even more specific subjects.

In addition to the use of letters and numbers to denote subjects, the Library of Congress call numbers make frequent use of cutter numbers that indicate something further about the subject of the document. For example, the Dewey Decimal Classification might indicate a hierarchical relationship of places on Earth, classifying documents dealing with these places by hemisphere, then by country, then by region of that country, and so forth. The Library of Congress Classification uses its own variation of this scheme to divide places alphabetically. For example, U.S. states are represented in the Library of Congress system with these additional alphanumeric designations:

• .A2 Alabama
• .A4 Alaska
• .A6 Arizona
• .A8 Arkansas
• .C2 California

Similarly, when treating individual subjects, the Library of Congress system may classify them alphabetically. For types of cats, for example, LC indicates the name of the breed:

• .A6 Angora
• .B8 Burmese
• .C6 Colorpoint
• .P4 Persian

When not used to indicate the subject or form of a document, the additional notation in the call number is used to subdivide works alphabetically, generally by the author’s last name. For example, the book Burmese Cats: Everything About Acquisition, Care, Nutrition, Behavior, Health Care, and Breeding (1995), by Carolyn M. Vella, would have this call number:

• SF
• 449
• .B8
• V45
• 1995

In this example, the alphabetical notation SF indicates that the work deals with animal culture, while 449 specifies the book’s subclass: cats. The notation .B8 further specifies Burmese cats. The fourth line is the cutter number, an alphanumeric combination, V45, that identifies the author’s last name, Vella. Finally, the notation 1995 designates the year in which the book was published.

Although Library of Congress Classification, like Dewey, has a hierarchical structure to it, this is not reflected in its notation. In classifying cats treated as pets, the following breakdown results:

• SF 446 Pictorial works
• 446.5 Behavior
• 446.6 Training
• SF 447 Culture and care
• 447.5 Breeding
• 447.6 Feeding
• SF 449 By breed, A-Z

The notation uses decimal numbers to fit in new subjects where needed. If LC’s notation worked in the same way that Dewey’s works, then as one went from the notation SF 447.5 (breeding) to SF 447 one would expect to be taken to the broader class of which breeding of cats was only a part. For example, in the Dewey Decimal Classification system, a detailed subclass of 636.825 designates Asian short-haired cats, but the more general number 636.82 represents, simply, short-haired cats. In the nonhierarchical notation used by the Library of Congress Classification, however, one goes from the subclass for breeding of cats (SF 447.5) to the equal subclass for culture and care of cats (SF 447). In other words, the LC does not permit libraries to adjust or abridge numbers to go to a broader class, as is done by libraries using Dewey Decimal Classification.

Libraries using LC Classification must accept the class numbers completely as assigned by the Library of Congress rather than abridge them as libraries using the Dewey Decimal Classification system might do. This requirement restricts a library’s flexibility in customizing a classification number to fit the size and nature of its collection, but the requirement also provides for a major strength of LC Classification: the ability of libraries to share classification work without having to concern themselves with how other libraries may have tailored the number to fit local needs. The ability to share classification work among all libraries using LC Classification was a major factor in the decision of many academic and research libraries to abandon the Dewey Decimal Classification system in favor of the LC system.

B.3.

Universal Decimal Classification

Another major classification system, widely used in Europe, Latin America, Russia, and Japan, is the Universal Decimal Classification (UDC). First presented in Belgium in 1895 by bibliographers Paul Otlet and Henri La Fontaine, it was designed to facilitate their organization of a universal bibliography of all recorded knowledge. Initially based on the fifth edition of the Dewey Decimal Classification, the Universal Decimal Classification combines notation to express multiple concepts. For example, 940(=395) indicates a work on the history of Vikings in Europe—940 is the top-level notation designating a work on the history of Europe, and 395 is the bottom-level notation denoting a study of Vikings.

The major purpose of the Universal Decimal Classification is to identify the content of documents. This is different from the Dewey and Library of Congress schemes, which also aim to locate items on the library’s shelves. If a library is also using the Universal Decimal Classification number for shelf location, the assigned top-level call number generally serves that purpose. Since its inception, the Universal Decimal system has developed increased capacity to express multiple concepts by combining notation. The system’s ability to represent multiple subjects of a document and to express the complex relationships of those subjects has made the Universal Decimal Classification a valuable tool in retrieving information from computerized databases. The Universal Decimal Classification system is issued by the International Federation for Documentation, in The Hague, Netherlands, which is responsible for its ongoing revision.

B.4.

Other Classification Systems

Although the Dewey Decimal, Library of Congress, and Universal Decimal classification systems are used worldwide, librarians have developed alternative classification systems that are used in various countries around the world. For example, in 1933 Indian librarian Shiyali Ramamrita Ranganathan introduced the Colon Classification system, which classifies all knowledge into broad, fundamental concepts. The Colon system then divides these concepts into several distinguishing characteristics, which Ranganathan called facets. The classification system uses colons (:) to distinguish between the various facets in a single notation. The name of the Colon Classification system is derived from its use of the colon in its notation scheme. Although use of the Colon Classification system is limited to a few Indian libraries, Ranganathan’s concept of facet analysis in classifying knowledge has been widely influential. Some of its key concepts have been adopted by subsequent editions of the Dewey and Universal systems, among others.

Libraries that serve users in very specialized fields of knowledge may also develop their own classification systems. They are especially likely to do so if the major library classifications do not adequately provide for the organization of the literature they collect. For example, organizations specializing in the study of mathematics developed the Mathematics Subject Classification to categorize material on advanced mathematical theory covered in specialized academic journals. The Mathematics Subject Classification allows mathematicians to classify works to a much greater degree of specificity than any of the major systems would allow.

Numerous classification systems have been created for use in other special libraries as well. The National Library of Medicine classification system, for example, has been adopted by most major medical libraries in the United States. That system, which is structured like the Library of Congress Classification, uses the letter W (unused by the Library of Congress system) for medical works. It also takes advantage of unused parts of the Library of Congress Classification class Q, for science. For other subject areas, the National Library of Medicine system applies the Library of Congress Classification unchanged.

C.

Subject Headings

Many single works in a library deal with multiple subjects. These works may be difficult to classify using traditional classification systems such as Dewey Decimal Classification or Library of Congress Classification, because these systems typically assign only one classification number to each item. As a result, only one subject is represented, and the work’s other topics are not expressed in the classification number. Users searching the library’s catalog under one of the alternate topics would never find that particular work. To avoid this problem, most libraries also identify their materials with subject headings, which assign multiple index terms to a work. This enables users to find works using any of a number of different search terms. Subject headings may be single words, compound words, or phrases that describe the subjects of a given document. Subject headings are particularly useful for executing online searches, which allow for a high degree of flexibility in identifying search terms.

In the United States, the two most frequently used systems for creating subject headings are those developed by the Library of Congress (LC) and the Sears List. The LC subject headings, first introduced in 1914, provide detailed terms for a vast number of topics. The LC headings are used in academic libraries, medium-sized to large public libraries, and many special libraries. The Sears List, developed in 1923 by American librarian Minnie Earl Sears, consists of a much smaller set of terms and is designed primarily for public and school libraries. The two lists are not entirely compatible and cannot be used in the same catalog.

Unlike index entries in an individual book, subject headings are generally used only if a major portion of the work deals with that particular subject. Under Library of Congress guidelines, at least 20 percent of a document must address a given subject for a subheading on that subject to be assigned to the book. Examples of LC subject headings include:

• Rivers
• Functional literacy
• Group homes for children
• Education, Preschool
• Burnout (Psychology)

All of the works in a library’s collection that deal with rivers in general would be listed in the catalog under the “Rivers” subject heading. Works dealing with a specific river, such the Mississippi River, would be indexed under the name of that river. “Rivers” is a relatively straightforward subject; subject headings may also represent complex concepts for works dealing with more than one theme. In order to express complex subjects, catalogers add subdivisions to the basic headings. These subdivisions can indicate, for example, specific time frames (20th century, 1860s, Middle Ages), geographical areas (Cairo, Pennsylvania, Canada), or the form of the document (bibliography, dictionary, fiction). Subdivisions may be added to the basic heading or combined with other subdivisions. They are usually separated from the subject heading by dashes. For example, the book National Dreams: Myth, Memory, and Canadian History (1997), by Daniel Francis, is listed under the following LC subject headings. Users could find the book by searching under any one of these headings:

• Group identity—Canada
• Popular culture—Canada
• Canada—History

Online computer catalogs provide far greater power for subject searching than do book or card catalogs. Most online catalogs allow users to execute keyword searches by using one or more of the important words in the subject-heading string. In keyword searching, library users can locate the subject heading “Universities and colleges—Graduate work—Examinations” simply by entering the words universities and examinations. This will retrieve catalog entries for all the library’s works on that subject. The keyword approach results in larger, less-targeted retrievals, often requiring the catalog user to review many records to find the works desired. The great advantage of keyword searching is that catalog users do not have to be familiar with the exact wording of the subject heading to locate desired items. In addition, they can easily browse large numbers of related works without having to physically locate the items on the shelves.

D.

Locating Library Materials

Visitors to a library can locate materials in different ways, depending on their own particular needs and interests. Someone looking for recreational reading material may wish to simply browse through the library’s selection of recently published best-sellers. Libraries typically maintain a section that showcases these popular materials. Most users, however, come to the library in search of information about a particular subject. The reference desk is often the best place for these users to start their search, because reference librarians are trained to help library users locate the materials they need. However, users must also learn how to search for information themselves if they are to make the best use of the resources the library has to offer.

Searching for and locating relevant information requires careful thought and strategy. Users can often find answers to their questions by first looking through general reference sources, such as encyclopedias, dictionaries, atlases, and other materials that are usually located near the library’s reference desk. These sources can provide overviews of the subject that may lead to more-detailed sources of information. Users looking for a wide range of literature on a particular subject can search through the library’s catalog, which provides an index of the library’s collection. In addition, users can search through various other indexes, abstracts, and databases. These sources provide references to relevant magazine and journal articles. The Internet can also be a useful source of information.

D.1.

Searching the Catalog

Library users can generally find the information they need by searching the library’s catalog, which is an index to all the materials in the library’s collection. Catalog entries typically list each item’s author, its title, its subjects, the date it was published, the name of its publisher, and for some materials, the names of editors, illustrators, or translators. Users can search for items in most online catalogs by entering keywords in any of these categories. Users of specialized collections might have the option of searching for other characteristics of library materials as well. A rare-book collection, for example, might allow users to search for materials by the name of the printer or binder of the book.

By searching through the catalog, users can easily determine whether the library owns works by a particular author or whether it has a work with a specific title. For example, consider a user searching for the book What Is Natural: Coral Reef Crisis (1999), by Jan Sapp. This user could simply conduct a title search of the catalog by typing in What Is Natural: Coral Reef Crisis. Or, by searching under the last name of the author, Sapp, the user could see whether the library has this book or other works by that author.

Searching for materials on a particular subject can be more difficult than searching for materials by authors or title. Before beginning a subject search, the user should first carefully consider various aspects of the information needed, identifying keywords and significant concepts associated with the given subject. These words and concepts can function as possible search terms. If searching under one term turns up too many possible works to realistically examine, a more specific term might be more useful. Likewise, if a search term reveals too few items, the user might achieve more productive results by searching under a more general term.

Some libraries feature union catalogs, which list the holdings of multiple libraries. Users can search union catalogs for materials that are unavailable at their local library but that may be accessible through interlibrary loan. For more information on library catalogs, see the subsection Catalogs in the Organization of Resources section of this article.

D.2.

Searching Indexes, Abstracts, and Databases

Even though library catalogs contain listings for every item in a given library’s collection, catalogs do not list individual articles in the library’s magazines and scholarly journals. To find details of articles on a given subject, library users must consult indexes, abstracts, or databases. These resources provide information on articles contained in periodicals, which are publications such as newspapers, magazines, and journals that are issued at regular intervals. Each index, abstract, or database typically focuses on a particular subject or range of related subjects. For example, some indexes list information about articles on art, whereas others contain information about articles on medical issues.

An index of periodicals lists citations containing bibliographic information about each article, including article title, author, publication title, and date of publication. An abstract contains the same information that a periodical index contains, as well as a paragraph or even a few paragraphs summarizing the article. Library databases are indexes and abstracts organized for easy access on a computer. Library databases are typically stored on CD-ROM or accessed via the Internet. Nearly all libraries have printed abstracts and indexes of periodical literature, but periodical information at most libraries is more complete on computer databases.

The Reader’s Guide to Periodical Literature is the best-known print index to English-language periodicals of general interest. Published twice per month, the Reader’s Guide lists articles in more than 150 magazines commonly subscribed to by public and school libraries. It arranges its listings alphabetically by author and subject, but not by title. The Reader’s Guide generally lists six pieces of information in each citation: article title, author, publication title, volume number, page number(s), and date of publication. The Reader’s Guide is cumulated regularly. This means that listings in the latest issues are merged with the previous issue, so that to find recent articles, users need to consult only two or three issues of the Reader’s Guide. Each of the older, bound volumes of the Reader’s Guide covers a two-year period. Some smaller libraries subscribe only to the Abridged Reader’s Guide, which indexes about 45 magazines. The Reader’s Guide series contains listings as far back as 1890. An earlier index, Poole’s Index, provides reference information for English-language articles published from 1802 to 1890. Although the Reader’s Guide is still available in public and school libraries, most library patrons now use computer databases to find magazine and journal articles.

Computer databases typically cover a particular subject or range of subjects. For example, the PsychLIT database contains bibliographic information on articles in the field of psychology. The Modern Language Association Bibliography contains citations for articles in the arts and humanities. The Educational Resources Information Center (ERIC) maintains a database of articles from education journals. Most databases offer only indexed or abstracted information, but some databases, known as full-text databases, provide the entire text of articles. Searching strategies can vary considerably from one database to the next, but most databases give tips to guide users in searching the particular database. In addition, reference librarians are specially trained to assist users in searching through databases.

Many public, academic, and school libraries have compendiums of computer databases, such as the InfoTrac catalogs of databases. Introduced in 1985, InfoTrac catalogs integrate many different kinds of databases into a single collection that can be accessed on CD-ROM or via the Internet. For example, patrons of public or academic libraries can use a single InfoTrac catalog to search computer databases of general interest magazines, government publications, academic journals, legal publications, and health-related periodicals. InfoTrac catalogs in school libraries may be tailored to support classroom assignments at various grade levels. These catalogs typically include computer databases containing the full text of articles in leading magazines, newspapers, and reference books.

D.3.

Finding Materials on the Library Shelves

Catalog citations indicate each item’s call number, which classifies the subject of the work and also identifies the item’s location on the library shelves. After finding an item in the catalog, a user can refer to maps in the library indicating the general placement of works within a wide range of call numbers. For example, a library using the Library of Congress Classification system might place together on one floor all of its works with call numbers ranging from H (social sciences) through P (languages and literature). Another floor might hold the library’s works with call numbers ranging from Q (science) through Z (library science). Signs on each row of shelves indicate the more specific range of materials located there. For example, one row of shelves might contain works with Library of Congress call numbers from PS3511 through PS3523. Each book in the library’s collection will display the call number on the book’s spine or on the outside of the back cover. Because call numbers indicate the subject content of a given work as well as its location, once a user finds one relevant item on the shelf, he or she may find other useful items simply by browsing through the materials in the same location.

Finding periodicals in the library is similar to finding books. After a user finds a useful article citation in a library database, abstract, or index, he or she must determine whether the library owns the periodical in which the article appears. The user can determine whether the library owns the publication by conducting a search of the library’s catalog by publication title. Most libraries arrange all of their periodicals in one general location in the library. Therefore, if the library subscribes to the periodical in question, the user can generally find the publication by searching for the magazine or journal title on the shelves of the periodical section. Some libraries also maintain periodical archives on microfilm (a small roll of film printed with rows of very small images that can be viewed using a library’s microfilm viewer), microfiche (similar to microfilm, but printed on a small sheet), and CD-ROM.

The shelves on which a library’s materials are arranged are known as stacks. Open stacks are accessible to patrons for selecting their own books and other materials. Some libraries have such large collections that many books have to be kept in closed stacks, which are not open to the public. To obtain books from closed stacks, the patron fills out a call slip, writing on it the call number, author, and title of the requested book. A librarian then gives the patron a number, which is also written on the slip. A library assistant finds the book in the closed stacks. In large libraries the number given to the patron may be flashed on a lighted board when the book is ready to be picked up.

V.

Borrowing Library Materials

The great majority of libraries allow users to borrow materials from their collections, and many public libraries consider this their most important service to users. Libraries that lend their materials to users are known as circulating libraries or lending libraries. Users borrow library materials from the circulation department, which keeps track of the library’s collections. The circulation desk is typically located near the entrance of the library. To ensure equitable distr