What is a Primary Source?
A primary source is something written or produced in the time period you are investigating. Primary sources include letters, speeches, diaries, newspaper articles from the time, oral history interviews of people from the time, documents, photographs, artifacts, and anything else that provides firsthand accounts about a person or event. This definition also applies to primary sources found on the Internet. A letter written by President Lincoln in 1862, whether scanned, transcribed, or otherwise reproduced, is a primary source for a student researching the Civil War era. A newspaper article about the Battle of Gettysburg written by a contemporary in July 1863 is a primary source. An article about the battle published in June 2001 and not written by an eyewitness or participant is not a primary source (unless the project was about 2001). The memories of a person who took part in the battle also can serve as a primary source because he or she was an eyewitness to and a participant in this historical event at the time. However, an interview with an expert (such as a professor of Civil War history) is not a primary source UNLESS that expert actually lived through and has firsthand knowledge of the events being described (highly unlikely for a Civil War historian!).
What is a Secondary Source?
A second source is a source by an author who was not an eyewitness or a participant in the historical event or period. Secondary sources are interpretations of primary sources, research, and study. Secondary sources provide context for a historical event. For example, high school history textbooks and history books about a particular topic are secondary sources; so are biographies, newspaper retrospectives, and reference books such as encyclopedias. This definition also applies to interpretations found on the Internet.