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Using the Library of Congress Online: A Guide for Middle and High School Students

Types of Sources

This page provides definitions of the various formats and kinds of sources available at the Library of Congress.

Primary Sources

Primary sources are the raw materials of history—original documents and objects that were created at the time under study. They are different from secondary sources, accounts that retell, analyze, or interpret events, usually at a distance of time or place. From the Dictionary for Library and Information Science, "In scholarship, a document or record containing firsthand information or original data on a topic, used in preparing a derivative work."

EXAMPLES: Primary sources include original manuscripts, periodical articles reporting original research or thought, diaries, memoirs, letters, journals, photographs, drawings, posters, film footage, sheet music, speeches, songs, interviews, government documents, public records, eyewitness accounts, newspaper clippings, memoirs, audio recordings, maps, oral histories, census data, etc.

Secondary Sources

Secondary sources are accounts that retell, analyze, or interpret events, usually at a distance of time or place. From the Dictionary for Library and Information Science, "Any published or unpublished work that is one step removed from the original source, usually describing, summarizing, analyzing, evaluating, derived from, or based on primary source materials... also refers to material other than primary sources used in the preparation of a written work."

EXAMPLES: A review, critical analysis, second-person account, historical study, encyclopedia, biographies, etc.

These represent some key types of information sources. Definitions modified from the Dictionary of Archives Terminology External from the Society of American Archivists and the Merriam Webster online dictionary.
Government Documents Resources created by national, state and local governments to document the activities of government or provide information about the locality and its people.
Journals Collections of articles that provide the most up-to-date research from academia and industries. The content can include literature reviews, case or research studies, or information on specific processes.
Manuscripts Unpublished documents, including handwritten documents and an author's draft of a book, article, or other work submitted for publication.
Maps Graphic representations of features of the Earth or another celestial body. Maps are typically drawn to scale using a projection technique and may include political boundaries and geological features, among other elements.
Moving Images Visual works that have the appearance of movement, including motion pictures, video, and flip books.
Newspapers Newspapers can cover current topics, historical events, and/or local information. Newspaper collections can be good places for exploring issues and events at the local, regional, national, or global level. They are published and distributed daily, weekly, or at some other regular and usually short interval.
Oral Histories Interviews that record an individual's personal recollections of the past and historical events. The audio or video recordings, transcripts, and other materials that capture and are associated with such an interview.
Photographs and Prints

A photograph is still picture formed on a light-sensitive surface using an optical system, such as a camera, and fixed by a photochemical process. A print is a copy of an original work of art made by either creating a template out of wood, metal, stone or zinc, mesh cloth or another medium and placing ink, paint or another liquid on the template and transferring the image to another surface such as paper, fabric or plastic. Prints can also be made using digital media including laser or other forms of digital technology.

Political Cartoons A drawing that is often symbolic and usually intended as humor, caricature, or satire and comment on public and usually political matters.
Reference Material Reference can provide background information on your topic. Typically, reference material comes in the form of encyclopedias, dictionaries, handbooks, yearbooks, atlases, and more.
Sheet Music A document that includes musical notation and lyrics to a song.
Sound Recordings Resources on which sound has been recorded for distribution or reproduction. Includes performances or spoken work presentations provided on a recordable medium including paper, wire, wax, tape or electronic format.