The second of the two main functions of libraries is directed at actively exploiting the collection to satisfy the information needs of library users.
Circulation
Although many of the libraries in antiquity were accessible to the literate public, this was almost certainly for reference only. Some monastic libraries, however, are known to have allowed the monks to borrow books for study in their cells; the Rule of St. Benedict explicitly permitted this, and the librarian exacted penance from any monk unable to confirm that he had actually read his book. Some university libraries may have lent books to members of their faculties, but the notion of lending, or circulating, libraries did not become popular until the 18th century.
The rapid development of public libraries in the 19th century led to the extension of the practice and to the introduction of various systems for the recording of loans. All the early systems depended on the use of one or more cards on which were recorded the name of the book, the name of the borrower, and the date on which the book should be returned. Many libraries now use a computerized circulation system that records information about both the user and the material in circulation.
Reference and retrieval
Open access to the shelves and the facility to borrow books mean that much of the use of a modern library is at the free choice of the reader; scholars and scientists continue to emphasize the value of browsing among the shelves of a well-arranged library. “Chance favours only the prepared mind,” said Louis Pasteur, and serendipitous discoveries of useful information during the search for some other subject have become a familiar and welcome aspect of using a library or other information service.
In reference service, librarians have traditionally given personal help to readers in making the best use of collections to satisfy their information needs. The publication of printed catalogs and bibliographies, the accessibility of on-line catalogs and multimedia databases, and the organizing of interlibrary cooperation have widened the range of resources available to the individual reader. As a result, librarians increasingly are called upon to help users determine the most efficient tool to use in their research. In scholarly libraries, assistance to readers once was generally limited to explaining the layout of the library and the use of the catalog; in universities, members of the faculty would have been expected to know the literature of their subject better than any librarian. But in public libraries, and still more so in special libraries in the fields of science and technology, readers have long sought guidance about information on their subject as well as about the library. This process has been greatly extended by the enormous increases in research worldwide and in the quantity of information and publications available in many languages and by the excellence of the indexes, abstracts, bibliographies, and databases that help to control the documentation of this massive output.
The subject search is one of the areas on which advancing technology has had the greatest impact. In many libraries, a variety of computer-based information retrieval systems provide ready access to details about off-site as well as on-site materials. For example, one development in subject access increases the amount of information that is available within library catalogs by including details from the table of contents or from a book’s index. Other systems, rather than just listing the abstract of a journal article, include the entire article. These full-text references eliminate the intermediate step characteristic of older systems in which users first performed an electronic search and then obtained the articles themselves in print or microfilm.
Reference services can be broadly divided into two main aspects, usually known as retrospective searching (or information retrieval) and current-awareness service (or selective dissemination of information). These terms indicate a specialization that has occurred in this core activity of libraries and that grew mainly out of the expansion of scientific and industrial research during and after World War I. Three factors strongly influenced this process. First, the increase in research and publication affected all types of libraries and brought with it a similar increase in subject specialization. Second, working scientists, accustomed to referring to reports in published papers, were content to leave the organizing of information searches to a colleague who knew and understood their work. And, third, the widespread application of scientific research in industry provided an extra stimulus to the division of labour because of the necessity for speedy application of results to gain commercial success in production.
Some information specialists have tried to draw a distinction between their reference work and the more general reference services of librarians, but in most countries there is close cooperation among all engaged in these professional activities. Most acknowledge a mutual interest and influence, while the range of duties allows, indeed requires, different emphases in different institutions.
All agree, however, in acknowledging the duty to assist users to find answers to inquiries and to carry out searches in existing literature. Such a service requires many qualities, personal and professional: a detailed knowledge of books, periodicals, and all other forms of record; an ability to search efficiently in catalogs, indexes, abstracts, and databases; and, above all, a sensitive understanding of each user’s needs. Matching the terms used by a reader in posing a question to the terms used by authors, indexers, and catalogers may well constitute one of the subtlest of professional skills.
Retrospective searching
The outcome of a search can take many forms, from a short, factual statement that gives the needed information to a short list of relevant references or a full-scale bibliography. In a computer search the first request often reveals that the database contains hundreds or even thousands of “hits,” or references relating to the topic requested. The number can be reduced by narrowing the subject, adding more specific details, or defining more precisely the information needed. When a reasonable number of hits has been reached, the computer can be instructed to display the details of a few references to show the reader whether or not the search has covered the right subject area. If it has, the set of references or abstracts may then be obtained in the form of a printout; if it has not, the search begins again using new terms for the request.
In the specialized information centre a professional researcher can conduct the search and provide a state-of-the-art review of the literature in narrative form instead of as a collection of references. The service represents a peak of efficiency on behalf of the client, who has neither the time nor the resources to make the same review. The value to industry and commerce has encouraged private individuals to become information brokers—i.e., to provide these services as a commercial enterprise.
Current-awareness service
The purpose of a current-awareness service is to inform the users about new acquisitions in their libraries. Public libraries in particular have used display boards and shelves to draw attention to recent additions, and many libraries produce complete or selective lists for circulation to patrons. Some libraries have adopted a practice of selective dissemination of information (sometimes referred to as SDI), whereby librarians conduct regular searches of databases to find references to new articles or other materials that fit a particular patron’s interest profile and forward the results of these searches to the patron.
One development of the concept of SDI in the electronic environment is a computer program that scans computer bulletin boards, electronic mail messages, and similar networked information resources and selects items that meet a user profile. Such programs enable individual users to keep abreast of the large amount of information available through computer networks without having to sift through much material that may be of little interest or relevance to them.
Community information
Library extension programs
The growth of information services in special libraries, followed by college and university libraries, also has influenced public library practice in library extension programs and community information services. Extension programs are usually arranged in cooperation with local educational organizations, university extramural courses, parent-teacher associations, and so on. In developing countries with nascent publishing and book trades, public libraries can offer valuable assistance to local authors, particularly those writing in indigenous languages, by providing facilities for authors to give lectures, hold seminars, and develop their own skills in direct relation with their potential readers. In European, African, and American libraries, poets or writers in residence have appeared as a part of similar action to bring authors and readers together.
Community awareness programs
In North America, community needs for informal information are often met by the public library’s community awareness service (or information and referral service), though practice is far from standardized. This community outreach program is an important feature in many mostly rural societies. The Jamaica Library Service, for example, has long made a practice of setting up a stall at farmers’ markets to supply up-to-date books and pamphlets on agriculture. Public libraries in China regularly set up special links with local factories for the supply of technical literature and specialist advisory staff.