A primary source is a physical record or document which contains a first hand account of an individual's thoughts, perceptions, or experiences during important periods of time throughout history.
The nature of primary sources varies greatly and is primarily dependent on the subject being studied. They can be journal entries, articles, books, tape recordings, paintings, songs, or interviews.
In contrast, a secondary source is typically defined as a scholarly or historical piece, often a book or article, which has been produced from the analysis of several primary sources.
The precision and impartiality of the sources is an invariable risk for historians who utilize them in their research and subsequent publications. Individuals tend to unconsciously alter events that occurred in the past in their own minds for varying reasons.
For this reason, the best, most well-rounded pieces of researched writing are often a combination of first and secondary sources along with the author's own analysis.