As defined by the Interlibrary Loan Code for the United States (see sidebar), "Interlibrary loan is the process by which a library requests material from, or supplies material to, another library. ... The purpose of interlibrary loan as defined by this code is to obtain, upon request of a library user, material not available in the user's local library."
Libraries should follow the Interlibrary Loan Code for the United States, originally approved in 1917 and most recently revised in 2015 by the Codes, Guidelines, and Technical Standards Committee of the Sharing and Transforming Access to Resources Section (STARS) of the Reference and User Services Association (RUSA), a division of the American Library Association. Revisions were approved by the RUSA Board of Directors on January 11, 2016. The ILL Code was also published in the Summer 2016 issue of the official RUSA journal, Reference & User Services Quarterly (v.55 no. 4, pp.306-307). The Explanatory Supplement accompanies the U.S. ILL Code and is intended to amplify specific sections, providing fuller explanation and specific examples.
The U.S. ILL Code is intended to provide guidelines for exchanges between libraries in the United States when no other agreement applies. The Code does not override individual, consortial, state, or regional agreements which may be more liberal or more prescriptive.
Libraries normally transmit requests electronically through OCLC, DOCLINE, or other networks. When an electronic means of making a request is unavailable, the ALA Interlibrary Loan Request Form (a fillable PDF -- see sidebar) may be used.
All libraries are encouraged to participate in international interlibrary loan activities. When seeking a loan from a library outside the United States, follow the guidelines set forth by the International Federation of Library Associations (IFLA) in International Resource Sharing and Document Delivery: Principles and Guidelines for Procedure.See also Guidelines for Best Practice in Interlibrary Loan and Document Delivery.