The definition of primary sources depends on the academic discipline and the context in which it is used. In the humanities, "Primary resources provide firsthand evidence of historical events. They are generally unpublished materials such as:
audio and video recordings,
In some instances, published materials can also be viewed as primary materials for the period in which they were written."
Historians use primary sources as evidence. Additional examples of primary sources are diaries, personal journals, government records, court records, property records, military reports, and military rosters.
In contrast, a secondary source is the typical history book which may discuss or analyze a person's life or work, an event or another historical topic. Secondary sources are accounts or interpretations of events by a person who doesn't have firsthand knowledge of the event. A good secondary source uses primary sources as evidence.