1.What are primary and secondary sources?

Ans:Primary sources are information provided by people who were involved in historical events or who witnessed the events.

Secondary sources are the records of people who did not directly participate in or witness the events they describe.

2.How do historians make sure that their sources are reliable?

Ans:They test their evidence using the 3 C's--credibility,consitency,corroboration--test

3.Why and when is it neccesary for historians to revise their interpretations of past events?