A primary source is an original document/image, the results of an experiment, statistical data, first-hand account, or creative work. A secondary source is something written about or using primary sources.
| Primary | Secondary |
|---|---|
| The text of The Gettysburg Address | An analysis of The Gettysburg Address |
| Census data for Detroit | A book about demographic changes in Detroit |
| A McDonald's commerical | A documentary about McDonald's advertising |
| The results of an experiment or clinical trial | An overview of different treatments options |
| An interview with a World War II veteran | A history book about World War II |