Primary sources are the evidence of history, original records or objects created by participants or observers at the time historical events occurred or even well after events, as in memoirs and oral histories. -- RUSA, a Division of ALA
Some examples:
Some primary sources may be created after an event by people who experienced the event. Some examples:
Infographic by Shonn Haren, Library at Wichita State University
Content credit: Pikes Peak Community College Libraries, History: Primary Sources