Primary sources allow researchers to get as close as possible to original ideas, events, and empirical research as possible. This may include creative works, contemporaneous accounts of events, and the publication of the results of empirical observations or research.
Secondary sources analyze, review, or summarize information in primary resources or other secondary resources. Sources presenting facts or descriptions about events are secondary unless they are based on direct participation or observation.
Tertiary sources provide overviews of topics by synthesizing information gathered from other resources.
The distinctions between primary, secondary, and tertiary sources can be ambiguous. An individual document may be a primary source in one context and a secondary source in another.
Adapted from VT Libraries' Primary, Secondary, and Tertiary Sources guide
| Subject | Primary | Secondary | Tertiary |
| Art | Painting | Critical review of the painting | Encyclopedia article on the artist |
| Chemistry | Chemical patent | Book about organic chemical reactions | Handbook of related organic reactions |
| History | Civil War diary | Journal article about a Civil War battle | List of Civil War battle sites |
| Literature | Novel or poem | Essay about themes in the work | Biography of the author |
| Physics | Conference proceeding on high energy physics | A book about the current state of the field of high energy physics | Dictionary of high energy physics |
| Politics | Geneva Convention | Article about prisoners of war | Chronology of treaties |
Adapted from UConn Library's Explore Information research guide