For some research projects, it is important (or you may be required) to use primary sources, instead of or in addition to secondary sources. So what's the difference?
"A primary source is an original object or document -- the raw material or first-hand information."
"primary sources are often empirical studies -- research where an experiment was done or a direct observation was made. The results of empirical studies are typically found in scholarly articles or papers delivered at conferences,..."
'Primary research articles can be identified by a commonly used format. Look for sections titled Methods (sometimes with variations, such as Materials and Methods), Results (usually followed with charts and statistical tables), and Discussion. Since a review of the literature is part of the research process, the article will also include bibliographic citations and a Works Cited section at the end."
"A secondary source is something written about a primary source."
"Secondary source materials can be articles in newspapers or popular magazines, book or movie reviews, or articles found in scholarly journals that discuss or evaluate someone else's original research."
Bridget Bower & John Henderson, http://www.ithacalibrary.com/sp/subjects/primary