Primary sources are first-hand evidence related to the time or event you are investigating. This includes accounts by participants or observers and a wide range of written, physical, audio or visual materials created at the time or later by someone with direct experience.
In the sciences and social sciences, primary sources or 'primary research' are original research experiments, studies, or observations written about by the researchers themselves.
If a primary source is direct first-hand evidence, then a secondary source is second-hand commentary including anything that investigates, comments on, brings together, or reviews those primary sources and other secondary sources.
| Discipline | Primary Source Examples | Secondary Source Examples |
| History |
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| Art & Literature |
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| Communications & Journalism |
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| Political Science |
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| Science & Social Science |
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What makes a source primary or secondary depends a lot on the questions you are researching, the context, and the discipline (subject). The same type of source might be primary for one use or discipline and secondary in another.
Documentaries: When studying history, a documentary about the Vietnam War is a secondary source because it brings together many primary sources about the war and makes an argument about them. In contrast, in the field of journalism, a documentary that investigates current political corruption would be a primary source because it involves original investigation.
Newspaper Articles: A newspaper article discussing a speech by the Speaker of the House would typically be a second-hand account of that speech (the primary source) and therefore the article is a secondary source. However, if we want to know how the media portrayed the Speaker of the House, or if the speech was so long ago the newspaper article is the only evidence left, it becomes a primary source.
Commentary or Criticism: A review of a movie is typically a secondary source commenting on the film itself. However, if you are researching the critical reception of a film that review would become a primary source.
Portions of this page were adapted from Scribbr.com "Primary and secondary sources"