Primary sources are materials (data, government documents, photographs, letters, etc.) that are used by scholars to produce secondary sources (original research published in books and scholarly articles). Some library databases include primary sources (e.g. historical newspaper articles), but many primary sources are found on the internet or in books.
Before using a primary source (especially one found through Google), you should:
Explore the image below -- mouseover the targets to learn more about the characteristics of a primary source. This example uses data tables (found on a website), but the elements discussed also apply to some books, articles, and websites.
"Municipal Solid Waste (MSW) in the United States: Facts and Figures."US Environmental Protection Agency. United States Environmental Protection Agency. 15 November 2012. Web. 23 January 2013.