The New York Public Library defines archives as "the records created by people and organizations as they lived and worked."

Archives usually consist of unpublished materials that accumulate organically over the course of time that were preserved for the enduring value of the information they contain, for their value as artifacts, or as evidence of the work or activities of the creator.  But they can contain just about anything that was created or saved by a person or organization. 

Materials relating to particular individuals, organizations, events and subjects will likely be scattered among myriad archival collections in multiple repositories. And those sources, even taken together, will be an incomplete record of the topic since they will be just the records that were saved and that have lasted.  Most of the records generated as people live and work aren’t saved at all.  So when you are looking for sources, remember that the historical record is likely incomplete.  Think about what might be missing.  And think creatively about where to find materials to answer your research questions. 

It can be very helpful to think in terms of collections, both personal papers and organizational records, and collections of images, ephemera, oral histories, maps, photographs, texts, historical periodicals, audio recordings, directories, government documents, etc.  Look for haystacks of sources rather than needles in haystacks.  

And think in terms of repositories.  The holdings of individual libraries and archives, when taken together, constitute unique cohesive resources.  When an archive holds a collection of photographs on a topic, for instance, chances are good that they will also hold manuscripts, books, periodicals, reference sources, and other materials related to those photographs.  So be certain to search at the repository level for materials when you find yourself exploring a collection held there.

Archival research can be simultaneously inspiring and tedious, enlightening and challenging, productive and time consuming.  More often than not, though, it is rewarding and worth the effort.

For practical advice and a realistic summary of what archival research is like, see Chapter 9, "Archival Research," in Zachary M. Schrag's The Princeton Guide to Historical Research. 

Following are definitions of some common archival terms.  For a comprehensive list, see the Dictionary of Archives Terminology, a handy online reference source from the Society of American Archivists.

Archival Collection - A broad term encompassing both personal papers and organizational records collections.

Archives - Records in any format created by or received and maintained by an organization that are determined to have permanent value. When housed in repositories outside the institution that created them, the collections are often called Organizational Records.

Artificial Collections - Collections of items assembled by an individual or institution from a variety of sources, usually on a topic or event (the sinking of the Titanic or the March on Washington, e.g.), a person (Abraham Lincoln, e.g.), or a format (menus, matchbook covers, postcards, or product advertising, e.g.). Examples include: The Radio Scripts Collection (NYPL Schomburg) and The World War I Collection (N-YHS). 

Institutional Repository or Archives - A repository that holds records created by or received by its parent institution. The Municipal Archives of the City of New York, The National Archives of the United States, and the Carnegie Hall Archives are institutional repositories. The archives of some organizations, especially commercial enterprises, exist solely to serve internal needs and outside researchers may have limited or no access to the records.

Manuscript Repository - An institution that collects historically valuable records of individuals, families, and organizations. The New-York Historical Society Library and The Manuscripts and Archives Division of the New York Public Library are manuscript repositories.

Original Order is the arrangement of materials established by the creator of the records. Archivists maintain original order whenever possible because the arrangement can shed light on how an individual or organization functioned and can also simplify access to the materials. When there is no discernible order, archivists sort the materials into series such as correspondence, writings, photographs, clippings, etc., in order to facilitate research and access.

Personal Papers or Manuscripts - Collections of materials in any format created by or received and maintained by an individual or family in the course of daily life. Examples include: the Harry Belafonte Papers (NYPL), the Audre Lord Papers (Spelman College), and the Shirley Hayes Papers (N-YHS).

Primary Sources & Secondary Sources - Materials that contain direct evidence, first-hand testimony, or an eyewitness account of a topic or event under investigation are considered primary sources. They can be published or unpublished items in any format, from handwritten letters, to objects, to the built environment. Secondary sources are works that analyze and interpret other sources. They use primary sources to solve research problems. The way you engage with a source determines whether it is a primary or secondary source for your project. Book reviews, for example, are typically considered secondary sources.  If the subject of your research is book reviews themselves, however, they would be primary sources for your project.

Provenance - A fundamental archival principle (also called respect des fonds) that requires that materials be grouped into collections according to their source, not according to their subject.

(Sources:  The Craft of Research by Wayne C. Booth, Gregory G. Colomb, Joseph M. Williams. Chicago: University of Chicago Press, c2008; Introduction to Archival Terminology, NARA; Theodore R. Schellenberg, Principles of Arrangement, Staff Information Paper Number 18, Published by the National Archives and Records Administration, Washington, DC, 1951.)