Primary and Secondary Sources

Primary sources provide firsthand testimony, direct evidence, or raw or original data about a topic. 
Examples include: 
  • Natural and social sciences: interviews or surveys, experimental results or findings, field notes, or other types of original data collected by a researcher
  • Literature or the arts:  poems, stories, novels, plays, musical scores, paintings, photographs, or other original texts, compositions, or artwork
  • History:  photographs, memoirs, letters, diaries, newspaper articles from the time of an event, government documents, oral histories, or other firsthand accounts. See our Guide for Finding Historical Primary Sources.

Secondary sources
offer an analysis, assessment, interpretation, or even summary of a topic, typically drawing on primary sources. Books, articles, or other sources that discuss or analyze a topic usually would be considered secondary sources. In the sciences, an example of a secondary source is a review article, while an example from literature would be a critical analysis of a novel or poem.

Important: Note that these categories are not mutually exclusive. The same document, or any other piece of evidence, may be a primary source in one investigation and secondary in another.

See these other pages for further help: