What's the difference between primary, secondary, and tertiary sources?
Answer
Primary Source
Different academic disciplines have different definitions of what constitutes a primary source.
- The humanities and social sciences define primary sources as materials produced at the time of an event, or by a person being studied or significantly involved with the event. Examples are letters, interviews, speeches, photographs, data sets, autobiographies, political documents, field notes, news produced at the time of an event etc. Physical objects such as artworks and artifacts can also be primary sources.
- In literature, a “primary source” or a “primary text” may refer to the literary work (novel, poem, etc.) that is being read/studied/analyzed.
- In the sciences, a primary source is a report on the results of an experiment by the person or group who performed it. They are usually published as scientific articles and may include original data.
Secondary Sources
Secondary sources may be defined as follows:
- A secondary source is a document which is based on the study and analysis of primary sources and other secondary sources. They interpret and analyze primary sources and provide the background necessary to understand the primary sources and context around the topic. Types of secondary sources include analysis, criticism, histories, and commentaries that may take the form of journal articles, biographies, reports, newspaper opinion and commentary, and other types of material.
- Secondary sources in the sciences are often referred to as review articles. They summarize, interpret, or analyze the findings of scientists to summarize the state of knowledge on a topic.
Tertiary Sources
A tertiary source compiles information derived from primary and secondary sources and uses that information to provide a broad overview of a topic. Examples include encyclopedias (including Wikipedia), dictionaries, and almanacs. Tertiary sources are usually not cited in academic projects unless there is a compelling reason to do so, such as when information from different sources on the same topic is contradictory or potentially incorrect.
For more information, see Evaluating Sources.