According to the Society of American Archivists, a primary source is “material that contains firsthand accounts of events and that was created contemporaneous to those events or later recalled by an eyewitness.”
"Primary sources emphasize the lack of intermediaries between the thing or events being studied and reports of those things or events based on the belief that firsthand accounts are more accurate.
Examples of primary sources include letters and diaries; government, church, and business records; oral histories; photographs, motion pictures, and videos; maps and land records; and blueprints.
Newspaper articles contemporaneous with the events described are traditionally considered primary sources, although the reporter may have compiled the story from witnesses, rather than being an eyewitness.
Artifacts and specimens may also be primary evidence if they are the object of study."