What are Primary Sources?
Primary sources are documents or physical objects which were created--in many formats--during the time an event happened. We can think of it as a "first-hand testimony." Examples of primary sources (hover over any in bold face to see an image from Adelphi Archives and Special Collections!):
Secondary sources offer evaluation, discussion, or analysis on primary sources and are usually created some time after the original time of the event. Examples of secondary sources:
The key to determining whether an item may be considered to be a primary source is to ask how soon after the event was the information recorded. This can be a problem with an autobiography, memoir, reminiscence, etc., if the author is working several years with only the memory of what happened. If you're not sure whether something is an acceptable primary source, ask your professor.
U.S. National Archives Administration home page provides helpful information when starting archival (primary source) research.