There are three types of sources:

1) Primary Sources

• Original materials that provide direct evidence or first-hand testimony concerning a topic or event.

• Primary sources can be contemporary sources created at the time when the event occurred (e.g., letters and newspaper articles) or later (such as, memoirs and oral history interviews).

• Primary sources may be published or unpublished.  Unpublished sources are unique materials (e.g., family papers) often referred to as archives and manuscripts.

• What constitutes a primary source varies by discipline. How the researcher uses the source generally determines whether it is a primary source or not.

2) Secondary Sources

• Works that interpret, analyze, and discuss the evidence provided by primary sources (e.g., scholarly books and articles).

• Secondary sources are generally a second-hand account or observation at least one step removed from the event.

• Secondary sources, however, can be considered to be primary sources depending on the context of their use. For example, Ken Burns' documentary of the Civil War is a secondary source for Civil War researchers, but a primary source for those studying documentary filmmaking.
  

3) Tertiary Sources

• Books or articles that synthesize or distill primary and secondary sources, often in a convenient, easy-to-read form (e.g., dictionaries, encyclopedias, indexes, and textbooks).

Each field of study has its own world of sources, conventions, and vocabularies.  The list that follows is not all inclusive, but will help you to identify primary sources in your own discipline.  In general, personal correspondence and diaries or journals are considered to be primary sources by all disciplines. If you are unsure that a source is considered primary by your discipline, ask your professor or a reference librarian for assistance.

• Archaeology/Anthropology: an artifact or object that provides evidence of a society, such as clothing, farming tools, household items, and buildings.


• Arts and Literature: the original artistic or literary work that forms the basis for a criticism or review, such as feature films, musical compositions, sound recordings, paintings, novels, plays, and poems.


• Biology: research or lab notes, genetic evidence, plant specimens, technical reports, and other reports of original research or discoveries (e.g., conference papers and proceedings, dissertations, scholarly articles).


• Business: market research or surveys, anything that documents a corporation's activities, such as annual reports, meeting minutes, legal documents, marketing materials, and financial records.


• Communication: websites, blogs, broadcast recordings and transcripts, advertisements and commercials, public opinion polls, and magazines (e.g., Rolling Stone).


• Engineering: design notes, patents, conference proceedings, technical reports, and field surveys.


• Geography: field notes, census data, maps, satellite images, and aerial photographs.


• History: government documents (e.g., treaty, birth certificate), photographs, store account books, artifacts (such as those listed for archaelogy/anthropology), maps, legal and financial documents, and census records.


• Law: court decisions, trial trancripts, and law codes.